test helpers: move test-* to t/helper/ subdirectory

This keeps top dir a bit less crowded. And because these programs are
for testing purposes, it makes sense that they stay somewhere in t/

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

35 files changed, 2316 insertions, 0 deletions

diff --git a/t/helper/.gitignore b/t/helper/.gitignore
new file mode 100644
index 0000000000..d6e8b36798
--- /dev/null
+++ b/t/helper/.gitignore
@@ -0,0 +1,33 @@
+/test-chmtime
+/test-ctype
+/test-config
+/test-date
+/test-delta
+/test-dump-cache-tree
+/test-dump-split-index
+/test-dump-untracked-cache
+/test-fake-ssh
+/test-scrap-cache-tree
+/test-genrandom
+/test-hashmap
+/test-index-version
+/test-line-buffer
+/test-match-trees
+/test-mergesort
+/test-mktemp
+/test-parse-options
+/test-path-utils
+/test-prio-queue
+/test-read-cache
+/test-regex
+/test-revision-walking
+/test-run-command
+/test-sha1
+/test-sha1-array
+/test-sigchain
+/test-string-list
+/test-submodule-config
+/test-subprocess
+/test-svn-fe
+/test-urlmatch-normalization
+/test-wildmatch
diff --git a/t/helper/test-chmtime.c b/t/helper/test-chmtime.c
new file mode 100644
index 0000000000..dfe8a83261
--- /dev/null
+++ b/t/helper/test-chmtime.c
@@ -0,0 +1,119 @@
+/*
+ * This program can either change modification time of the given
+ * file(s) or just print it. The program does not change atime or
+ * ctime (their values are explicitly preserved).
+ *
+ * The mtime can be changed to an absolute value:
+ *
+ *	test-chmtime =<seconds> file...
+ *
+ * Relative to the current time as returned by time(3):
+ *
+ *	test-chmtime =+<seconds> (or =-<seconds>) file...
+ *
+ * Or relative to the current mtime of the file:
+ *
+ *	test-chmtime <seconds> file...
+ *	test-chmtime +<seconds> (or -<seconds>) file...
+ *
+ * Examples:
+ *
+ * To just print the mtime use --verbose and set the file mtime offset to 0:
+ *
+ *	test-chmtime -v +0 file
+ *
+ * To set the mtime to current time:
+ *
+ *	test-chmtime =+0 file
+ *
+ */
+#include "git-compat-util.h"
+#include <utime.h>
+
+static const char usage_str[] = "-v|--verbose (+|=|=+|=-|-)<seconds> <file>...";
+
+static int timespec_arg(const char *arg, long int *set_time, int *set_eq)
+{
+	char *test;
+	const char *timespec = arg;
+	*set_eq = (*timespec == '=') ? 1 : 0;
+	if (*set_eq) {
+		timespec++;
+		if (*timespec == '+') {
+			*set_eq = 2; /* relative "in the future" */
+			timespec++;
+		}
+	}
+	*set_time = strtol(timespec, &test, 10);
+	if (*test) {
+		fprintf(stderr, "Not a base-10 integer: %s\n", arg + 1);
+		return 0;
+	}
+	if ((*set_eq && *set_time < 0) || *set_eq == 2) {
+		time_t now = time(NULL);
+		*set_time += now;
+	}
+	return 1;
+}
+
+int main(int argc, char *argv[])
+{
+	static int verbose;
+
+	int i = 1;
+	/* no mtime change by default */
+	int set_eq = 0;
+	long int set_time = 0;
+
+	if (argc < 3)
+		goto usage;
+
+	if (strcmp(argv[i], "--verbose") == 0 || strcmp(argv[i], "-v") == 0) {
+		verbose = 1;
+		++i;
+	}
+	if (timespec_arg(argv[i], &set_time, &set_eq))
+		++i;
+	else
+		goto usage;
+
+	for (; i < argc; i++) {
+		struct stat sb;
+		struct utimbuf utb;
+
+		if (stat(argv[i], &sb) < 0) {
+			fprintf(stderr, "Failed to stat %s: %s\n",
+			        argv[i], strerror(errno));
+			return 1;
+		}
+
+#ifdef GIT_WINDOWS_NATIVE
+		if (!(sb.st_mode & S_IWUSR) &&
+				chmod(argv[i], sb.st_mode | S_IWUSR)) {
+			fprintf(stderr, "Could not make user-writable %s: %s",
+				argv[i], strerror(errno));
+			return 1;
+		}
+#endif
+
+		utb.actime = sb.st_atime;
+		utb.modtime = set_eq ? set_time : sb.st_mtime + set_time;
+
+		if (verbose) {
+			uintmax_t mtime = utb.modtime < 0 ? 0: utb.modtime;
+			printf("%"PRIuMAX"\t%s\n", mtime, argv[i]);
+		}
+
+		if (utb.modtime != sb.st_mtime && utime(argv[i], &utb) < 0) {
+			fprintf(stderr, "Failed to modify time on %s: %s\n",
+			        argv[i], strerror(errno));
+			return 1;
+		}
+	}
+
+	return 0;
+
+usage:
+	fprintf(stderr, "usage: %s %s\n", argv[0], usage_str);
+	return 1;
+}
diff --git a/t/helper/test-config.c b/t/helper/test-config.c
new file mode 100644
index 0000000000..6a77552210
--- /dev/null
+++ b/t/helper/test-config.c
@@ -0,0 +1,152 @@
+#include "cache.h"
+#include "string-list.h"
+
+/*
+ * This program exposes the C API of the configuration mechanism
+ * as a set of simple commands in order to facilitate testing.
+ *
+ * Reads stdin and prints result of command to stdout:
+ *
+ * get_value -> prints the value with highest priority for the entered key
+ *
+ * get_value_multi -> prints all values for the entered key in increasing order
+ *		     of priority
+ *
+ * get_int -> print integer value for the entered key or die
+ *
+ * get_bool -> print bool value for the entered key or die
+ *
+ * get_string -> print string value for the entered key or die
+ *
+ * configset_get_value -> returns value with the highest priority for the entered key
+ * 			from a config_set constructed from files entered as arguments.
+ *
+ * configset_get_value_multi -> returns value_list for the entered key sorted in
+ * 				ascending order of priority from a config_set
+ * 				constructed from files entered as arguments.
+ *
+ * Examples:
+ *
+ * To print the value with highest priority for key "foo.bAr Baz.rock":
+ * 	test-config get_value "foo.bAr Baz.rock"
+ *
+ */
+
+
+int main(int argc, char **argv)
+{
+	int i, val;
+	const char *v;
+	const struct string_list *strptr;
+	struct config_set cs;
+	git_configset_init(&cs);
+
+	if (argc < 2) {
+		fprintf(stderr, "Please, provide a command name on the command-line\n");
+		goto exit1;
+	} else if (argc == 3 && !strcmp(argv[1], "get_value")) {
+		if (!git_config_get_value(argv[2], &v)) {
+			if (!v)
+				printf("(NULL)\n");
+			else
+				printf("%s\n", v);
+			goto exit0;
+		} else {
+			printf("Value not found for \"%s\"\n", argv[2]);
+			goto exit1;
+		}
+	} else if (argc == 3 && !strcmp(argv[1], "get_value_multi")) {
+		strptr = git_config_get_value_multi(argv[2]);
+		if (strptr) {
+			for (i = 0; i < strptr->nr; i++) {
+				v = strptr->items[i].string;
+				if (!v)
+					printf("(NULL)\n");
+				else
+					printf("%s\n", v);
+			}
+			goto exit0;
+		} else {
+			printf("Value not found for \"%s\"\n", argv[2]);
+			goto exit1;
+		}
+	} else if (argc == 3 && !strcmp(argv[1], "get_int")) {
+		if (!git_config_get_int(argv[2], &val)) {
+			printf("%d\n", val);
+			goto exit0;
+		} else {
+			printf("Value not found for \"%s\"\n", argv[2]);
+			goto exit1;
+		}
+	} else if (argc == 3 && !strcmp(argv[1], "get_bool")) {
+		if (!git_config_get_bool(argv[2], &val)) {
+			printf("%d\n", val);
+			goto exit0;
+		} else {
+			printf("Value not found for \"%s\"\n", argv[2]);
+			goto exit1;
+		}
+	} else if (argc == 3 && !strcmp(argv[1], "get_string")) {
+		if (!git_config_get_string_const(argv[2], &v)) {
+			printf("%s\n", v);
+			goto exit0;
+		} else {
+			printf("Value not found for \"%s\"\n", argv[2]);
+			goto exit1;
+		}
+	} else if (!strcmp(argv[1], "configset_get_value")) {
+		for (i = 3; i < argc; i++) {
+			int err;
+			if ((err = git_configset_add_file(&cs, argv[i]))) {
+				fprintf(stderr, "Error (%d) reading configuration file %s.\n", err, argv[i]);
+				goto exit2;
+			}
+		}
+		if (!git_configset_get_value(&cs, argv[2], &v)) {
+			if (!v)
+				printf("(NULL)\n");
+			else
+				printf("%s\n", v);
+			goto exit0;
+		} else {
+			printf("Value not found for \"%s\"\n", argv[2]);
+			goto exit1;
+		}
+	} else if (!strcmp(argv[1], "configset_get_value_multi")) {
+		for (i = 3; i < argc; i++) {
+			int err;
+			if ((err = git_configset_add_file(&cs, argv[i]))) {
+				fprintf(stderr, "Error (%d) reading configuration file %s.\n", err, argv[i]);
+				goto exit2;
+			}
+		}
+		strptr = git_configset_get_value_multi(&cs, argv[2]);
+		if (strptr) {
+			for (i = 0; i < strptr->nr; i++) {
+				v = strptr->items[i].string;
+				if (!v)
+					printf("(NULL)\n");
+				else
+					printf("%s\n", v);
+			}
+			goto exit0;
+		} else {
+			printf("Value not found for \"%s\"\n", argv[2]);
+			goto exit1;
+		}
+	}
+
+	die("%s: Please check the syntax and the function name", argv[0]);
+
+exit0:
+	git_configset_clear(&cs);
+	return 0;
+
+exit1:
+	git_configset_clear(&cs);
+	return 1;
+
+exit2:
+	git_configset_clear(&cs);
+	return 2;
+}
diff --git a/t/helper/test-ctype.c b/t/helper/test-ctype.c
new file mode 100644
index 0000000000..707a821f03
--- /dev/null
+++ b/t/helper/test-ctype.c
@@ -0,0 +1,42 @@
+#include "cache.h"
+
+static int rc;
+
+static void report_error(const char *class, int ch)
+{
+	printf("%s classifies char %d (0x%02x) wrongly\n", class, ch, ch);
+	rc = 1;
+}
+
+static int is_in(const char *s, int ch)
+{
+	/* We can't find NUL using strchr.  It's classless anyway. */
+	if (ch == '\0')
+		return 0;
+	return !!strchr(s, ch);
+}
+
+#define TEST_CLASS(t,s) {			\
+	int i;					\
+	for (i = 0; i < 256; i++) {		\
+		if (is_in(s, i) != t(i))	\
+			report_error(#t, i);	\
+	}					\
+}
+
+#define DIGIT "0123456789"
+#define LOWER "abcdefghijklmnopqrstuvwxyz"
+#define UPPER "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+
+int main(int argc, char **argv)
+{
+	TEST_CLASS(isdigit, DIGIT);
+	TEST_CLASS(isspace, " \n\r\t");
+	TEST_CLASS(isalpha, LOWER UPPER);
+	TEST_CLASS(isalnum, LOWER UPPER DIGIT);
+	TEST_CLASS(is_glob_special, "*?[\\");
+	TEST_CLASS(is_regex_special, "$()*+.?[\\^{|");
+	TEST_CLASS(is_pathspec_magic, "!\"#%&',-/:;<=>@_`~");
+
+	return rc;
+}
diff --git a/t/helper/test-date.c b/t/helper/test-date.c
new file mode 100644
index 0000000000..63f373557e
--- /dev/null
+++ b/t/helper/test-date.c
@@ -0,0 +1,73 @@
+#include "cache.h"
+
+static const char *usage_msg = "\n"
+"  test-date show [time_t]...\n"
+"  test-date parse [date]...\n"
+"  test-date approxidate [date]...\n";
+
+static void show_dates(char **argv, struct timeval *now)
+{
+	struct strbuf buf = STRBUF_INIT;
+
+	for (; *argv; argv++) {
+		time_t t = atoi(*argv);
+		show_date_relative(t, 0, now, &buf);
+		printf("%s -> %s\n", *argv, buf.buf);
+	}
+	strbuf_release(&buf);
+}
+
+static void parse_dates(char **argv, struct timeval *now)
+{
+	struct strbuf result = STRBUF_INIT;
+
+	for (; *argv; argv++) {
+		unsigned long t;
+		int tz;
+
+		strbuf_reset(&result);
+		parse_date(*argv, &result);
+		if (sscanf(result.buf, "%lu %d", &t, &tz) == 2)
+			printf("%s -> %s\n",
+			       *argv, show_date(t, tz, DATE_MODE(ISO8601)));
+		else
+			printf("%s -> bad\n", *argv);
+	}
+	strbuf_release(&result);
+}
+
+static void parse_approxidate(char **argv, struct timeval *now)
+{
+	for (; *argv; argv++) {
+		time_t t;
+		t = approxidate_relative(*argv, now);
+		printf("%s -> %s\n", *argv, show_date(t, 0, DATE_MODE(ISO8601)));
+	}
+}
+
+int main(int argc, char **argv)
+{
+	struct timeval now;
+	const char *x;
+
+	x = getenv("TEST_DATE_NOW");
+	if (x) {
+		now.tv_sec = atoi(x);
+		now.tv_usec = 0;
+	}
+	else
+		gettimeofday(&now, NULL);
+
+	argv++;
+	if (!*argv)
+		usage(usage_msg);
+	if (!strcmp(*argv, "show"))
+		show_dates(argv+1, &now);
+	else if (!strcmp(*argv, "parse"))
+		parse_dates(argv+1, &now);
+	else if (!strcmp(*argv, "approxidate"))
+		parse_approxidate(argv+1, &now);
+	else
+		usage(usage_msg);
+	return 0;
+}
diff --git a/t/helper/test-delta.c b/t/helper/test-delta.c
new file mode 100644
index 0000000000..4595cd6433
--- /dev/null
+++ b/t/helper/test-delta.c
@@ -0,0 +1,78 @@
+/*
+ * test-delta.c: test code to exercise diff-delta.c and patch-delta.c
+ *
+ * (C) 2005 Nicolas Pitre <nico@fluxnic.net>
+ *
+ * This code is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "git-compat-util.h"
+#include "delta.h"
+#include "cache.h"
+
+static const char usage_str[] =
+	"test-delta (-d|-p) <from_file> <data_file> <out_file>";
+
+int main(int argc, char *argv[])
+{
+	int fd;
+	struct stat st;
+	void *from_buf, *data_buf, *out_buf;
+	unsigned long from_size, data_size, out_size;
+
+	if (argc != 5 || (strcmp(argv[1], "-d") && strcmp(argv[1], "-p"))) {
+		fprintf(stderr, "usage: %s\n", usage_str);
+		return 1;
+	}
+
+	fd = open(argv[2], O_RDONLY);
+	if (fd < 0 || fstat(fd, &st)) {
+		perror(argv[2]);
+		return 1;
+	}
+	from_size = st.st_size;
+	from_buf = mmap(NULL, from_size, PROT_READ, MAP_PRIVATE, fd, 0);
+	if (from_buf == MAP_FAILED) {
+		perror(argv[2]);
+		close(fd);
+		return 1;
+	}
+	close(fd);
+
+	fd = open(argv[3], O_RDONLY);
+	if (fd < 0 || fstat(fd, &st)) {
+		perror(argv[3]);
+		return 1;
+	}
+	data_size = st.st_size;
+	data_buf = mmap(NULL, data_size, PROT_READ, MAP_PRIVATE, fd, 0);
+	if (data_buf == MAP_FAILED) {
+		perror(argv[3]);
+		close(fd);
+		return 1;
+	}
+	close(fd);
+
+	if (argv[1][1] == 'd')
+		out_buf = diff_delta(from_buf, from_size,
+				     data_buf, data_size,
+				     &out_size, 0);
+	else
+		out_buf = patch_delta(from_buf, from_size,
+				      data_buf, data_size,
+				      &out_size);
+	if (!out_buf) {
+		fprintf(stderr, "delta operation failed (returned NULL)\n");
+		return 1;
+	}
+
+	fd = open (argv[4], O_WRONLY|O_CREAT|O_TRUNC, 0666);
+	if (fd < 0 || write_in_full(fd, out_buf, out_size) != out_size) {
+		perror(argv[4]);
+		return 1;
+	}
+
+	return 0;
+}
diff --git a/t/helper/test-dump-cache-tree.c b/t/helper/test-dump-cache-tree.c
new file mode 100644
index 0000000000..bb53c0aa65
--- /dev/null
+++ b/t/helper/test-dump-cache-tree.c
@@ -0,0 +1,67 @@
+#include "cache.h"
+#include "tree.h"
+#include "cache-tree.h"
+
+
+static void dump_one(struct cache_tree *it, const char *pfx, const char *x)
+{
+	if (it->entry_count < 0)
+		printf("%-40s %s%s (%d subtrees)\n",
+		       "invalid", x, pfx, it->subtree_nr);
+	else
+		printf("%s %s%s (%d entries, %d subtrees)\n",
+		       sha1_to_hex(it->sha1), x, pfx,
+		       it->entry_count, it->subtree_nr);
+}
+
+static int dump_cache_tree(struct cache_tree *it,
+			   struct cache_tree *ref,
+			   const char *pfx)
+{
+	int i;
+	int errs = 0;
+
+	if (!it || !ref)
+		/* missing in either */
+		return 0;
+
+	if (it->entry_count < 0) {
+		/* invalid */
+		dump_one(it, pfx, "");
+		dump_one(ref, pfx, "#(ref) ");
+	}
+	else {
+		dump_one(it, pfx, "");
+		if (hashcmp(it->sha1, ref->sha1) ||
+		    ref->entry_count != it->entry_count ||
+		    ref->subtree_nr != it->subtree_nr) {
+			/* claims to be valid but is lying */
+			dump_one(ref, pfx, "#(ref) ");
+			errs = 1;
+		}
+	}
+
+	for (i = 0; i < it->subtree_nr; i++) {
+		char path[PATH_MAX];
+		struct cache_tree_sub *down = it->down[i];
+		struct cache_tree_sub *rdwn;
+
+		rdwn = cache_tree_sub(ref, down->name);
+		xsnprintf(path, sizeof(path), "%s%.*s/", pfx, down->namelen, down->name);
+		if (dump_cache_tree(down->cache_tree, rdwn->cache_tree, path))
+			errs = 1;
+	}
+	return errs;
+}
+
+int main(int ac, char **av)
+{
+	struct index_state istate;
+	struct cache_tree *another = cache_tree();
+	if (read_cache() < 0)
+		die("unable to read index file");
+	istate = the_index;
+	istate.cache_tree = another;
+	cache_tree_update(&istate, WRITE_TREE_DRY_RUN);
+	return dump_cache_tree(active_cache_tree, another, "");
+}
diff --git a/t/helper/test-dump-split-index.c b/t/helper/test-dump-split-index.c
new file mode 100644
index 0000000000..861d28c9b6
--- /dev/null
+++ b/t/helper/test-dump-split-index.c
@@ -0,0 +1,36 @@
+#include "cache.h"
+#include "split-index.h"
+#include "ewah/ewok.h"
+
+static void show_bit(size_t pos, void *data)
+{
+	printf(" %d", (int)pos);
+}
+
+int main(int ac, char **av)
+{
+	struct split_index *si;
+	int i;
+
+	do_read_index(&the_index, av[1], 1);
+	printf("own %s\n", sha1_to_hex(the_index.sha1));
+	si = the_index.split_index;
+	if (!si) {
+		printf("not a split index\n");
+		return 0;
+	}
+	printf("base %s\n", sha1_to_hex(si->base_sha1));
+	for (i = 0; i < the_index.cache_nr; i++) {
+		struct cache_entry *ce = the_index.cache[i];
+		printf("%06o %s %d\t%s\n", ce->ce_mode,
+		       sha1_to_hex(ce->sha1), ce_stage(ce), ce->name);
+	}
+	printf("replacements:");
+	if (si->replace_bitmap)
+		ewah_each_bit(si->replace_bitmap, show_bit, NULL);
+	printf("\ndeletions:");
+	if (si->delete_bitmap)
+		ewah_each_bit(si->delete_bitmap, show_bit, NULL);
+	printf("\n");
+	return 0;
+}
diff --git a/t/helper/test-dump-untracked-cache.c b/t/helper/test-dump-untracked-cache.c
new file mode 100644
index 0000000000..0a1c285246
--- /dev/null
+++ b/t/helper/test-dump-untracked-cache.c
@@ -0,0 +1,66 @@
+#include "cache.h"
+#include "dir.h"
+
+static int compare_untracked(const void *a_, const void *b_)
+{
+	const char *const *a = a_;
+	const char *const *b = b_;
+	return strcmp(*a, *b);
+}
+
+static int compare_dir(const void *a_, const void *b_)
+{
+	const struct untracked_cache_dir *const *a = a_;
+	const struct untracked_cache_dir *const *b = b_;
+	return strcmp((*a)->name, (*b)->name);
+}
+
+static void dump(struct untracked_cache_dir *ucd, struct strbuf *base)
+{
+	int i, len;
+	qsort(ucd->untracked, ucd->untracked_nr, sizeof(*ucd->untracked),
+	      compare_untracked);
+	qsort(ucd->dirs, ucd->dirs_nr, sizeof(*ucd->dirs),
+	      compare_dir);
+	len = base->len;
+	strbuf_addf(base, "%s/", ucd->name);
+	printf("%s %s", base->buf,
+	       sha1_to_hex(ucd->exclude_sha1));
+	if (ucd->recurse)
+		fputs(" recurse", stdout);
+	if (ucd->check_only)
+		fputs(" check_only", stdout);
+	if (ucd->valid)
+		fputs(" valid", stdout);
+	printf("\n");
+	for (i = 0; i < ucd->untracked_nr; i++)
+		printf("%s\n", ucd->untracked[i]);
+	for (i = 0; i < ucd->dirs_nr; i++)
+		dump(ucd->dirs[i], base);
+	strbuf_setlen(base, len);
+}
+
+int main(int ac, char **av)
+{
+	struct untracked_cache *uc;
+	struct strbuf base = STRBUF_INIT;
+
+	/* Hack to avoid modifying the untracked cache when we read it */
+	ignore_untracked_cache_config = 1;
+
+	setup_git_directory();
+	if (read_cache() < 0)
+		die("unable to read index file");
+	uc = the_index.untracked;
+	if (!uc) {
+		printf("no untracked cache\n");
+		return 0;
+	}
+	printf("info/exclude %s\n", sha1_to_hex(uc->ss_info_exclude.sha1));
+	printf("core.excludesfile %s\n", sha1_to_hex(uc->ss_excludes_file.sha1));
+	printf("exclude_per_dir %s\n", uc->exclude_per_dir);
+	printf("flags %08x\n", uc->dir_flags);
+	if (uc->root)
+		dump(uc->root, &base);
+	return 0;
+}
diff --git a/t/helper/test-fake-ssh.c b/t/helper/test-fake-ssh.c
new file mode 100644
index 0000000000..980de216e1
--- /dev/null
+++ b/t/helper/test-fake-ssh.c
@@ -0,0 +1,30 @@
+#include "git-compat-util.h"
+#include "run-command.h"
+#include "strbuf.h"
+
+int main(int argc, char **argv)
+{
+	const char *trash_directory = getenv("TRASH_DIRECTORY");
+	struct strbuf buf = STRBUF_INIT;
+	FILE *f;
+	int i;
+	const char *child_argv[] = { NULL, NULL };
+
+	/* First, print all parameters into $TRASH_DIRECTORY/ssh-output */
+	if (!trash_directory)
+		die("Need a TRASH_DIRECTORY!");
+	strbuf_addf(&buf, "%s/ssh-output", trash_directory);
+	f = fopen(buf.buf, "w");
+	if (!f)
+		die("Could not write to %s", buf.buf);
+	for (i = 0; i < argc; i++)
+		fprintf(f, "%s%s", i > 0 ? " " : "", i > 0 ? argv[i] : "ssh:");
+	fprintf(f, "\n");
+	fclose(f);
+
+	/* Now, evaluate the *last* parameter */
+	if (argc < 2)
+		return 0;
+	child_argv[0] = argv[argc - 1];
+	return run_command_v_opt(child_argv, RUN_USING_SHELL);
+}
diff --git a/t/helper/test-genrandom.c b/t/helper/test-genrandom.c
new file mode 100644
index 0000000000..54824d0754
--- /dev/null
+++ b/t/helper/test-genrandom.c
@@ -0,0 +1,33 @@
+/*
+ * Simple random data generator used to create reproducible test files.
+ * This is inspired from POSIX.1-2001 implementation example for rand().
+ * Copyright (C) 2007 by Nicolas Pitre, licensed under the GPL version 2.
+ */
+
+#include "git-compat-util.h"
+
+int main(int argc, char *argv[])
+{
+	unsigned long count, next = 0;
+	unsigned char *c;
+
+	if (argc < 2 || argc > 3) {
+		fprintf(stderr, "usage: %s <seed_string> [<size>]\n", argv[0]);
+		return 1;
+	}
+
+	c = (unsigned char *) argv[1];
+	do {
+		next = next * 11 + *c;
+	} while (*c++);
+
+	count = (argc == 3) ? strtoul(argv[2], NULL, 0) : -1L;
+
+	while (count--) {
+		next = next * 1103515245 + 12345;
+		if (putchar((next >> 16) & 0xff) == EOF)
+			return -1;
+	}
+
+	return 0;
+}
diff --git a/t/helper/test-hashmap.c b/t/helper/test-hashmap.c
new file mode 100644
index 0000000000..cc2891dd97
--- /dev/null
+++ b/t/helper/test-hashmap.c
@@ -0,0 +1,264 @@
+#include "git-compat-util.h"
+#include "hashmap.h"
+
+struct test_entry
+{
+	struct hashmap_entry ent;
+	/* key and value as two \0-terminated strings */
+	char key[FLEX_ARRAY];
+};
+
+static const char *get_value(const struct test_entry *e)
+{
+	return e->key + strlen(e->key) + 1;
+}
+
+static int test_entry_cmp(const struct test_entry *e1,
+		const struct test_entry *e2, const char* key)
+{
+	return strcmp(e1->key, key ? key : e2->key);
+}
+
+static int test_entry_cmp_icase(const struct test_entry *e1,
+		const struct test_entry *e2, const char* key)
+{
+	return strcasecmp(e1->key, key ? key : e2->key);
+}
+
+static struct test_entry *alloc_test_entry(int hash, char *key, int klen,
+		char *value, int vlen)
+{
+	struct test_entry *entry = malloc(sizeof(struct test_entry) + klen
+			+ vlen + 2);
+	hashmap_entry_init(entry, hash);
+	memcpy(entry->key, key, klen + 1);
+	memcpy(entry->key + klen + 1, value, vlen + 1);
+	return entry;
+}
+
+#define HASH_METHOD_FNV 0
+#define HASH_METHOD_I 1
+#define HASH_METHOD_IDIV10 2
+#define HASH_METHOD_0 3
+#define HASH_METHOD_X2 4
+#define TEST_SPARSE 8
+#define TEST_ADD 16
+#define TEST_SIZE 100000
+
+static unsigned int hash(unsigned int method, unsigned int i, const char *key)
+{
+	unsigned int hash = 0;
+	switch (method & 3)
+	{
+	case HASH_METHOD_FNV:
+		hash = strhash(key);
+		break;
+	case HASH_METHOD_I:
+		hash = i;
+		break;
+	case HASH_METHOD_IDIV10:
+		hash = i / 10;
+		break;
+	case HASH_METHOD_0:
+		hash = 0;
+		break;
+	}
+
+	if (method & HASH_METHOD_X2)
+		hash = 2 * hash;
+	return hash;
+}
+
+/*
+ * Test performance of hashmap.[ch]
+ * Usage: time echo "perfhashmap method rounds" | test-hashmap
+ */
+static void perf_hashmap(unsigned int method, unsigned int rounds)
+{
+	struct hashmap map;
+	char buf[16];
+	struct test_entry **entries;
+	unsigned int *hashes;
+	unsigned int i, j;
+
+	entries = malloc(TEST_SIZE * sizeof(struct test_entry *));
+	hashes = malloc(TEST_SIZE * sizeof(int));
+	for (i = 0; i < TEST_SIZE; i++) {
+		snprintf(buf, sizeof(buf), "%i", i);
+		entries[i] = alloc_test_entry(0, buf, strlen(buf), "", 0);
+		hashes[i] = hash(method, i, entries[i]->key);
+	}
+
+	if (method & TEST_ADD) {
+		/* test adding to the map */
+		for (j = 0; j < rounds; j++) {
+			hashmap_init(&map, (hashmap_cmp_fn) test_entry_cmp, 0);
+
+			/* add entries */
+			for (i = 0; i < TEST_SIZE; i++) {
+				hashmap_entry_init(entries[i], hashes[i]);
+				hashmap_add(&map, entries[i]);
+			}
+
+			hashmap_free(&map, 0);
+		}
+	} else {
+		/* test map lookups */
+		hashmap_init(&map, (hashmap_cmp_fn) test_entry_cmp, 0);
+
+		/* fill the map (sparsely if specified) */
+		j = (method & TEST_SPARSE) ? TEST_SIZE / 10 : TEST_SIZE;
+		for (i = 0; i < j; i++) {
+			hashmap_entry_init(entries[i], hashes[i]);
+			hashmap_add(&map, entries[i]);
+		}
+
+		for (j = 0; j < rounds; j++) {
+			for (i = 0; i < TEST_SIZE; i++) {
+				hashmap_get_from_hash(&map, hashes[i],
+						      entries[i]->key);
+			}
+		}
+
+		hashmap_free(&map, 0);
+	}
+}
+
+#define DELIM " \t\r\n"
+
+/*
+ * Read stdin line by line and print result of commands to stdout:
+ *
+ * hash key -> strhash(key) memhash(key) strihash(key) memihash(key)
+ * put key value -> NULL / old value
+ * get key -> NULL / value
+ * remove key -> NULL / old value
+ * iterate -> key1 value1\nkey2 value2\n...
+ * size -> tablesize numentries
+ *
+ * perfhashmap method rounds -> test hashmap.[ch] performance
+ */
+int main(int argc, char *argv[])
+{
+	char line[1024];
+	struct hashmap map;
+	int icase;
+
+	/* init hash map */
+	icase = argc > 1 && !strcmp("ignorecase", argv[1]);
+	hashmap_init(&map, (hashmap_cmp_fn) (icase ? test_entry_cmp_icase
+			: test_entry_cmp), 0);
+
+	/* process commands from stdin */
+	while (fgets(line, sizeof(line), stdin)) {
+		char *cmd, *p1 = NULL, *p2 = NULL;
+		int l1 = 0, l2 = 0, hash = 0;
+		struct test_entry *entry;
+
+		/* break line into command and up to two parameters */
+		cmd = strtok(line, DELIM);
+		/* ignore empty lines */
+		if (!cmd || *cmd == '#')
+			continue;
+
+		p1 = strtok(NULL, DELIM);
+		if (p1) {
+			l1 = strlen(p1);
+			hash = icase ? strihash(p1) : strhash(p1);
+			p2 = strtok(NULL, DELIM);
+			if (p2)
+				l2 = strlen(p2);
+		}
+
+		if (!strcmp("hash", cmd) && l1) {
+
+			/* print results of different hash functions */
+			printf("%u %u %u %u\n", strhash(p1), memhash(p1, l1),
+					strihash(p1), memihash(p1, l1));
+
+		} else if (!strcmp("add", cmd) && l1 && l2) {
+
+			/* create entry with key = p1, value = p2 */
+			entry = alloc_test_entry(hash, p1, l1, p2, l2);
+
+			/* add to hashmap */
+			hashmap_add(&map, entry);
+
+		} else if (!strcmp("put", cmd) && l1 && l2) {
+
+			/* create entry with key = p1, value = p2 */
+			entry = alloc_test_entry(hash, p1, l1, p2, l2);
+
+			/* add / replace entry */
+			entry = hashmap_put(&map, entry);
+
+			/* print and free replaced entry, if any */
+			puts(entry ? get_value(entry) : "NULL");
+			free(entry);
+
+		} else if (!strcmp("get", cmd) && l1) {
+
+			/* lookup entry in hashmap */
+			entry = hashmap_get_from_hash(&map, hash, p1);
+
+			/* print result */
+			if (!entry)
+				puts("NULL");
+			while (entry) {
+				puts(get_value(entry));
+				entry = hashmap_get_next(&map, entry);
+			}
+
+		} else if (!strcmp("remove", cmd) && l1) {
+
+			/* setup static key */
+			struct hashmap_entry key;
+			hashmap_entry_init(&key, hash);
+
+			/* remove entry from hashmap */
+			entry = hashmap_remove(&map, &key, p1);
+
+			/* print result and free entry*/
+			puts(entry ? get_value(entry) : "NULL");
+			free(entry);
+
+		} else if (!strcmp("iterate", cmd)) {
+
+			struct hashmap_iter iter;
+			hashmap_iter_init(&map, &iter);
+			while ((entry = hashmap_iter_next(&iter)))
+				printf("%s %s\n", entry->key, get_value(entry));
+
+		} else if (!strcmp("size", cmd)) {
+
+			/* print table sizes */
+			printf("%u %u\n", map.tablesize, map.size);
+
+		} else if (!strcmp("intern", cmd) && l1) {
+
+			/* test that strintern works */
+			const char *i1 = strintern(p1);
+			const char *i2 = strintern(p1);
+			if (strcmp(i1, p1))
+				printf("strintern(%s) returns %s\n", p1, i1);
+			else if (i1 == p1)
+				printf("strintern(%s) returns input pointer\n", p1);
+			else if (i1 != i2)
+				printf("strintern(%s) != strintern(%s)", i1, i2);
+			else
+				printf("%s\n", i1);
+
+		} else if (!strcmp("perfhashmap", cmd) && l1 && l2) {
+
+			perf_hashmap(atoi(p1), atoi(p2));
+
+		} else {
+
+			printf("Unknown command %s\n", cmd);
+
+		}
+	}
+
+	hashmap_free(&map, 1);
+	return 0;
+}
diff --git a/t/helper/test-index-version.c b/t/helper/test-index-version.c
new file mode 100644
index 0000000000..05d4699c4a
--- /dev/null
+++ b/t/helper/test-index-version.c
@@ -0,0 +1,14 @@
+#include "cache.h"
+
+int main(int argc, char **argv)
+{
+	struct cache_header hdr;
+	int version;
+
+	memset(&hdr,0,sizeof(hdr));
+	if (read(0, &hdr, sizeof(hdr)) != sizeof(hdr))
+		return 0;
+	version = ntohl(hdr.hdr_version);
+	printf("%d\n", version);
+	return 0;
+}
diff --git a/t/helper/test-line-buffer.c b/t/helper/test-line-buffer.c
new file mode 100644
index 0000000000..1e58f0476f
--- /dev/null
+++ b/t/helper/test-line-buffer.c
@@ -0,0 +1,91 @@
+/*
+ * test-line-buffer.c: code to exercise the svn importer's input helper
+ */
+
+#include "git-compat-util.h"
+#include "strbuf.h"
+#include "vcs-svn/line_buffer.h"
+
+static uint32_t strtouint32(const char *s)
+{
+	char *end;
+	uintmax_t n = strtoumax(s, &end, 10);
+	if (*s == '\0' || *end != '\0')
+		die("invalid count: %s", s);
+	return (uint32_t) n;
+}
+
+static void handle_command(const char *command, const char *arg, struct line_buffer *buf)
+{
+	switch (*command) {
+	case 'b':
+		if (starts_with(command, "binary ")) {
+			struct strbuf sb = STRBUF_INIT;
+			strbuf_addch(&sb, '>');
+			buffer_read_binary(buf, &sb, strtouint32(arg));
+			fwrite(sb.buf, 1, sb.len, stdout);
+			strbuf_release(&sb);
+			return;
+		}
+	case 'c':
+		if (starts_with(command, "copy ")) {
+			buffer_copy_bytes(buf, strtouint32(arg));
+			return;
+		}
+	case 's':
+		if (starts_with(command, "skip ")) {
+			buffer_skip_bytes(buf, strtouint32(arg));
+			return;
+		}
+	default:
+		die("unrecognized command: %s", command);
+	}
+}
+
+static void handle_line(const char *line, struct line_buffer *stdin_buf)
+{
+	const char *arg = strchr(line, ' ');
+	if (!arg)
+		die("no argument in line: %s", line);
+	handle_command(line, arg + 1, stdin_buf);
+}
+
+int main(int argc, char *argv[])
+{
+	struct line_buffer stdin_buf = LINE_BUFFER_INIT;
+	struct line_buffer file_buf = LINE_BUFFER_INIT;
+	struct line_buffer *input = &stdin_buf;
+	const char *filename;
+	char *s;
+
+	if (argc == 1)
+		filename = NULL;
+	else if (argc == 2)
+		filename = argv[1];
+	else
+		usage("test-line-buffer [file | &fd] < script");
+
+	if (buffer_init(&stdin_buf, NULL))
+		die_errno("open error");
+	if (filename) {
+		if (*filename == '&') {
+			if (buffer_fdinit(&file_buf, strtouint32(filename + 1)))
+				die_errno("error opening fd %s", filename + 1);
+		} else {
+			if (buffer_init(&file_buf, filename))
+				die_errno("error opening %s", filename);
+		}
+		input = &file_buf;
+	}
+
+	while ((s = buffer_read_line(&stdin_buf)))
+		handle_line(s, input);
+
+	if (filename && buffer_deinit(&file_buf))
+		die("error reading from %s", filename);
+	if (buffer_deinit(&stdin_buf))
+		die("input error");
+	if (ferror(stdout))
+		die("output error");
+	return 0;
+}
diff --git a/t/helper/test-match-trees.c b/t/helper/test-match-trees.c
new file mode 100644
index 0000000000..4dad7095f1
--- /dev/null
+++ b/t/helper/test-match-trees.c
@@ -0,0 +1,26 @@
+#include "cache.h"
+#include "tree.h"
+
+int main(int ac, char **av)
+{
+	unsigned char hash1[20], hash2[20], shifted[20];
+	struct tree *one, *two;
+
+	setup_git_directory();
+
+	if (get_sha1(av[1], hash1))
+		die("cannot parse %s as an object name", av[1]);
+	if (get_sha1(av[2], hash2))
+		die("cannot parse %s as an object name", av[2]);
+	one = parse_tree_indirect(hash1);
+	if (!one)
+		die("not a tree-ish %s", av[1]);
+	two = parse_tree_indirect(hash2);
+	if (!two)
+		die("not a tree-ish %s", av[2]);
+
+	shift_tree(one->object.oid.hash, two->object.oid.hash, shifted, -1);
+	printf("shifted: %s\n", sha1_to_hex(shifted));
+
+	exit(0);
+}
diff --git a/t/helper/test-mergesort.c b/t/helper/test-mergesort.c
new file mode 100644
index 0000000000..ea3b959e94
--- /dev/null
+++ b/t/helper/test-mergesort.c
@@ -0,0 +1,52 @@
+#include "cache.h"
+#include "mergesort.h"
+
+struct line {
+	char *text;
+	struct line *next;
+};
+
+static void *get_next(const void *a)
+{
+	return ((const struct line *)a)->next;
+}
+
+static void set_next(void *a, void *b)
+{
+	((struct line *)a)->next = b;
+}
+
+static int compare_strings(const void *a, const void *b)
+{
+	const struct line *x = a, *y = b;
+	return strcmp(x->text, y->text);
+}
+
+int main(int argc, char **argv)
+{
+	struct line *line, *p = NULL, *lines = NULL;
+	struct strbuf sb = STRBUF_INIT;
+
+	for (;;) {
+		if (strbuf_getwholeline(&sb, stdin, '\n'))
+			break;
+		line = xmalloc(sizeof(struct line));
+		line->text = strbuf_detach(&sb, NULL);
+		if (p) {
+			line->next = p->next;
+			p->next = line;
+		} else {
+			line->next = NULL;
+			lines = line;
+		}
+		p = line;
+	}
+
+	lines = llist_mergesort(lines, get_next, set_next, compare_strings);
+
+	while (lines) {
+		printf("%s", lines->text);
+		lines = lines->next;
+	}
+	return 0;
+}
diff --git a/t/helper/test-mktemp.c b/t/helper/test-mktemp.c
new file mode 100644
index 0000000000..c8c54213a3
--- /dev/null
+++ b/t/helper/test-mktemp.c
@@ -0,0 +1,14 @@
+/*
+ * test-mktemp.c: code to exercise the creation of temporary files
+ */
+#include "git-compat-util.h"
+
+int main(int argc, char *argv[])
+{
+	if (argc != 2)
+		usage("Expected 1 parameter defining the temporary file template");
+
+	xmkstemp(xstrdup(argv[1]));
+
+	return 0;
+}
diff --git a/t/helper/test-parse-options.c b/t/helper/test-parse-options.c
new file mode 100644
index 0000000000..2c8c8f18ed
--- /dev/null
+++ b/t/helper/test-parse-options.c
@@ -0,0 +1,104 @@
+#include "cache.h"
+#include "parse-options.h"
+#include "string-list.h"
+
+static int boolean = 0;
+static int integer = 0;
+static unsigned long magnitude = 0;
+static unsigned long timestamp;
+static int abbrev = 7;
+static int verbose = 0, dry_run = 0, quiet = 0;
+static char *string = NULL;
+static char *file = NULL;
+static int ambiguous;
+static struct string_list list;
+
+static int length_callback(const struct option *opt, const char *arg, int unset)
+{
+	printf("Callback: \"%s\", %d\n",
+		(arg ? arg : "not set"), unset);
+	if (unset)
+		return 1; /* do not support unset */
+
+	*(int *)opt->value = strlen(arg);
+	return 0;
+}
+
+static int number_callback(const struct option *opt, const char *arg, int unset)
+{
+	*(int *)opt->value = strtol(arg, NULL, 10);
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	const char *prefix = "prefix/";
+	const char *usage[] = {
+		"test-parse-options <options>",
+		NULL
+	};
+	struct option options[] = {
+		OPT_BOOL(0, "yes", &boolean, "get a boolean"),
+		OPT_BOOL('D', "no-doubt", &boolean, "begins with 'no-'"),
+		{ OPTION_SET_INT, 'B', "no-fear", &boolean, NULL,
+		  "be brave", PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, 1 },
+		OPT_COUNTUP('b', "boolean", &boolean, "increment by one"),
+		OPT_BIT('4', "or4", &boolean,
+			"bitwise-or boolean with ...0100", 4),
+		OPT_NEGBIT(0, "neg-or4", &boolean, "same as --no-or4", 4),
+		OPT_GROUP(""),
+		OPT_INTEGER('i', "integer", &integer, "get a integer"),
+		OPT_INTEGER('j', NULL, &integer, "get a integer, too"),
+		OPT_MAGNITUDE('m', "magnitude", &magnitude, "get a magnitude"),
+		OPT_SET_INT(0, "set23", &integer, "set integer to 23", 23),
+		OPT_DATE('t', NULL, &timestamp, "get timestamp of <time>"),
+		OPT_CALLBACK('L', "length", &integer, "str",
+			"get length of <str>", length_callback),
+		OPT_FILENAME('F', "file", &file, "set file to <file>"),
+		OPT_GROUP("String options"),
+		OPT_STRING('s', "string", &string, "string", "get a string"),
+		OPT_STRING(0, "string2", &string, "str", "get another string"),
+		OPT_STRING(0, "st", &string, "st", "get another string (pervert ordering)"),
+		OPT_STRING('o', NULL, &string, "str", "get another string"),
+		OPT_NOOP_NOARG(0, "obsolete"),
+		OPT_STRING_LIST(0, "list", &list, "str", "add str to list"),
+		OPT_GROUP("Magic arguments"),
+		OPT_ARGUMENT("quux", "means --quux"),
+		OPT_NUMBER_CALLBACK(&integer, "set integer to NUM",
+			number_callback),
+		{ OPTION_COUNTUP, '+', NULL, &boolean, NULL, "same as -b",
+		  PARSE_OPT_NOARG | PARSE_OPT_NONEG | PARSE_OPT_NODASH },
+		{ OPTION_COUNTUP, 0, "ambiguous", &ambiguous, NULL,
+		  "positive ambiguity", PARSE_OPT_NOARG | PARSE_OPT_NONEG },
+		{ OPTION_COUNTUP, 0, "no-ambiguous", &ambiguous, NULL,
+		  "negative ambiguity", PARSE_OPT_NOARG | PARSE_OPT_NONEG },
+		OPT_GROUP("Standard options"),
+		OPT__ABBREV(&abbrev),
+		OPT__VERBOSE(&verbose, "be verbose"),
+		OPT__DRY_RUN(&dry_run, "dry run"),
+		OPT__QUIET(&quiet, "be quiet"),
+		OPT_END(),
+	};
+	int i;
+
+	argc = parse_options(argc, (const char **)argv, prefix, options, usage, 0);
+
+	printf("boolean: %d\n", boolean);
+	printf("integer: %d\n", integer);
+	printf("magnitude: %lu\n", magnitude);
+	printf("timestamp: %lu\n", timestamp);
+	printf("string: %s\n", string ? string : "(not set)");
+	printf("abbrev: %d\n", abbrev);
+	printf("verbose: %d\n", verbose);
+	printf("quiet: %s\n", quiet ? "yes" : "no");
+	printf("dry run: %s\n", dry_run ? "yes" : "no");
+	printf("file: %s\n", file ? file : "(not set)");
+
+	for (i = 0; i < list.nr; i++)
+		printf("list: %s\n", list.items[i].string);
+
+	for (i = 0; i < argc; i++)
+		printf("arg %02d: %s\n", i, argv[i]);
+
+	return 0;
+}
diff --git a/t/helper/test-path-utils.c b/t/helper/test-path-utils.c
new file mode 100644
index 0000000000..ba805b374c
--- /dev/null
+++ b/t/helper/test-path-utils.c
@@ -0,0 +1,262 @@
+#include "cache.h"
+#include "string-list.h"
+
+/*
+ * A "string_list_each_func_t" function that normalizes an entry from
+ * GIT_CEILING_DIRECTORIES.  If the path is unusable for some reason,
+ * die with an explanation.
+ */
+static int normalize_ceiling_entry(struct string_list_item *item, void *unused)
+{
+	char *ceil = item->string;
+
+	if (!*ceil)
+		die("Empty path is not supported");
+	if (!is_absolute_path(ceil))
+		die("Path \"%s\" is not absolute", ceil);
+	if (normalize_path_copy(ceil, ceil) < 0)
+		die("Path \"%s\" could not be normalized", ceil);
+	return 1;
+}
+
+static void normalize_argv_string(const char **var, const char *input)
+{
+	if (!strcmp(input, "<null>"))
+		*var = NULL;
+	else if (!strcmp(input, "<empty>"))
+		*var = "";
+	else
+		*var = input;
+
+	if (*var && (**var == '<' || **var == '('))
+		die("Bad value: %s\n", input);
+}
+
+struct test_data {
+	const char *from;  /* input:  transform from this ... */
+	const char *to;    /* output: ... to this.            */
+	const char *alternative; /* output: ... or this.      */
+};
+
+static int test_function(struct test_data *data, char *(*func)(char *input),
+	const char *funcname)
+{
+	int failed = 0, i;
+	char buffer[1024];
+	char *to;
+
+	for (i = 0; data[i].to; i++) {
+		if (!data[i].from)
+			to = func(NULL);
+		else {
+			xsnprintf(buffer, sizeof(buffer), "%s", data[i].from);
+			to = func(buffer);
+		}
+		if (!strcmp(to, data[i].to))
+			continue;
+		if (!data[i].alternative)
+			error("FAIL: %s(%s) => '%s' != '%s'\n",
+				funcname, data[i].from, to, data[i].to);
+		else if (!strcmp(to, data[i].alternative))
+			continue;
+		else
+			error("FAIL: %s(%s) => '%s' != '%s', '%s'\n",
+				funcname, data[i].from, to, data[i].to,
+				data[i].alternative);
+		failed = 1;
+	}
+	return failed;
+}
+
+static struct test_data basename_data[] = {
+	/* --- POSIX type paths --- */
+	{ NULL,              "."    },
+	{ "",                "."    },
+	{ ".",               "."    },
+	{ "..",              ".."   },
+	{ "/",               "/"    },
+	{ "//",              "/", "//" },
+	{ "///",             "/", "//" },
+	{ "////",            "/", "//" },
+	{ "usr",             "usr"  },
+	{ "/usr",            "usr"  },
+	{ "/usr/",           "usr"  },
+	{ "/usr//",          "usr"  },
+	{ "/usr/lib",        "lib"  },
+	{ "usr/lib",         "lib"  },
+	{ "usr/lib///",      "lib"  },
+
+#if defined(__MINGW32__) || defined(_MSC_VER)
+	/* --- win32 type paths --- */
+	{ "\\usr",           "usr"  },
+	{ "\\usr\\",         "usr"  },
+	{ "\\usr\\\\",       "usr"  },
+	{ "\\usr\\lib",      "lib"  },
+	{ "usr\\lib",        "lib"  },
+	{ "usr\\lib\\\\\\",  "lib"  },
+	{ "C:/usr",          "usr"  },
+	{ "C:/usr",          "usr"  },
+	{ "C:/usr/",         "usr"  },
+	{ "C:/usr//",        "usr"  },
+	{ "C:/usr/lib",      "lib"  },
+	{ "C:usr/lib",       "lib"  },
+	{ "C:usr/lib///",    "lib"  },
+	{ "C:",              "."    },
+	{ "C:a",             "a"    },
+	{ "C:/",             "/"    },
+	{ "C:///",           "/"    },
+	{ "\\",              "\\", "/" },
+	{ "\\\\",            "\\", "/" },
+	{ "\\\\\\",          "\\", "/" },
+#endif
+	{ NULL,              NULL   }
+};
+
+static struct test_data dirname_data[] = {
+	/* --- POSIX type paths --- */
+	{ NULL,              "."      },
+	{ "",                "."      },
+	{ ".",               "."      },
+	{ "..",              "."      },
+	{ "/",               "/"      },
+	{ "//",              "/", "//" },
+	{ "///",             "/", "//" },
+	{ "////",            "/", "//" },
+	{ "usr",             "."      },
+	{ "/usr",            "/"      },
+	{ "/usr/",           "/"      },
+	{ "/usr//",          "/"      },
+	{ "/usr/lib",        "/usr"   },
+	{ "usr/lib",         "usr"    },
+	{ "usr/lib///",      "usr"    },
+
+#if defined(__MINGW32__) || defined(_MSC_VER)
+	/* --- win32 type paths --- */
+	{ "\\",              "\\"     },
+	{ "\\\\",            "\\\\"   },
+	{ "\\usr",           "\\"     },
+	{ "\\usr\\",         "\\"     },
+	{ "\\usr\\\\",       "\\"     },
+	{ "\\usr\\lib",      "\\usr"  },
+	{ "usr\\lib",        "usr"    },
+	{ "usr\\lib\\\\\\",  "usr"    },
+	{ "C:a",             "C:."    },
+	{ "C:/",             "C:/"    },
+	{ "C:///",           "C:/"    },
+	{ "C:/usr",          "C:/"    },
+	{ "C:/usr/",         "C:/"    },
+	{ "C:/usr//",        "C:/"    },
+	{ "C:/usr/lib",      "C:/usr" },
+	{ "C:usr/lib",       "C:usr"  },
+	{ "C:usr/lib///",    "C:usr"  },
+	{ "\\\\\\",          "\\"     },
+	{ "\\\\\\\\",        "\\"     },
+	{ "C:",              "C:.", "." },
+#endif
+	{ NULL,              NULL     }
+};
+
+int main(int argc, char **argv)
+{
+	if (argc == 3 && !strcmp(argv[1], "normalize_path_copy")) {
+		char *buf = xmallocz(strlen(argv[2]));
+		int rv = normalize_path_copy(buf, argv[2]);
+		if (rv)
+			buf = "++failed++";
+		puts(buf);
+		return 0;
+	}
+
+	if (argc >= 2 && !strcmp(argv[1], "real_path")) {
+		while (argc > 2) {
+			puts(real_path(argv[2]));
+			argc--;
+			argv++;
+		}
+		return 0;
+	}
+
+	if (argc >= 2 && !strcmp(argv[1], "absolute_path")) {
+		while (argc > 2) {
+			puts(absolute_path(argv[2]));
+			argc--;
+			argv++;
+		}
+		return 0;
+	}
+
+	if (argc == 4 && !strcmp(argv[1], "longest_ancestor_length")) {
+		int len;
+		struct string_list ceiling_dirs = STRING_LIST_INIT_DUP;
+		char *path = xstrdup(argv[2]);
+
+		/*
+		 * We have to normalize the arguments because under
+		 * Windows, bash mangles arguments that look like
+		 * absolute POSIX paths or colon-separate lists of
+		 * absolute POSIX paths into DOS paths (e.g.,
+		 * "/foo:/foo/bar" might be converted to
+		 * "D:\Src\msysgit\foo;D:\Src\msysgit\foo\bar"),
+		 * whereas longest_ancestor_length() requires paths
+		 * that use forward slashes.
+		 */
+		if (normalize_path_copy(path, path))
+			die("Path \"%s\" could not be normalized", argv[2]);
+		string_list_split(&ceiling_dirs, argv[3], PATH_SEP, -1);
+		filter_string_list(&ceiling_dirs, 0,
+				   normalize_ceiling_entry, NULL);
+		len = longest_ancestor_length(path, &ceiling_dirs);
+		string_list_clear(&ceiling_dirs, 0);
+		free(path);
+		printf("%d\n", len);
+		return 0;
+	}
+
+	if (argc >= 4 && !strcmp(argv[1], "prefix_path")) {
+		char *prefix = argv[2];
+		int prefix_len = strlen(prefix);
+		int nongit_ok;
+		setup_git_directory_gently(&nongit_ok);
+		while (argc > 3) {
+			puts(prefix_path(prefix, prefix_len, argv[3]));
+			argc--;
+			argv++;
+		}
+		return 0;
+	}
+
+	if (argc == 4 && !strcmp(argv[1], "strip_path_suffix")) {
+		char *prefix = strip_path_suffix(argv[2], argv[3]);
+		printf("%s\n", prefix ? prefix : "(null)");
+		return 0;
+	}
+
+	if (argc == 3 && !strcmp(argv[1], "print_path")) {
+		puts(argv[2]);
+		return 0;
+	}
+
+	if (argc == 4 && !strcmp(argv[1], "relative_path")) {
+		struct strbuf sb = STRBUF_INIT;
+		const char *in, *prefix, *rel;
+		normalize_argv_string(&in, argv[2]);
+		normalize_argv_string(&prefix, argv[3]);
+		rel = relative_path(in, prefix, &sb);
+		if (!rel)
+			puts("(null)");
+		else
+			puts(strlen(rel) > 0 ? rel : "(empty)");
+		strbuf_release(&sb);
+		return 0;
+	}
+
+	if (argc == 2 && !strcmp(argv[1], "basename"))
+		return test_function(basename_data, basename, argv[1]);
+
+	if (argc == 2 && !strcmp(argv[1], "dirname"))
+		return test_function(dirname_data, dirname, argv[1]);
+
+	fprintf(stderr, "%s: unknown function name: %s\n", argv[0],
+		argv[1] ? argv[1] : "(there was none)");
+	return 1;
+}
diff --git a/t/helper/test-prio-queue.c b/t/helper/test-prio-queue.c
new file mode 100644
index 0000000000..7be72f0086
--- /dev/null
+++ b/t/helper/test-prio-queue.c
@@ -0,0 +1,39 @@
+#include "cache.h"
+#include "prio-queue.h"
+
+static int intcmp(const void *va, const void *vb, void *data)
+{
+	const int *a = va, *b = vb;
+	return *a - *b;
+}
+
+static void show(int *v)
+{
+	if (!v)
+		printf("NULL\n");
+	else
+		printf("%d\n", *v);
+	free(v);
+}
+
+int main(int argc, char **argv)
+{
+	struct prio_queue pq = { intcmp };
+
+	while (*++argv) {
+		if (!strcmp(*argv, "get"))
+			show(prio_queue_get(&pq));
+		else if (!strcmp(*argv, "dump")) {
+			int *v;
+			while ((v = prio_queue_get(&pq)))
+			       show(v);
+		}
+		else {
+			int *v = malloc(sizeof(*v));
+			*v = atoi(*argv);
+			prio_queue_put(&pq, v);
+		}
+	}
+
+	return 0;
+}
diff --git a/t/helper/test-read-cache.c b/t/helper/test-read-cache.c
new file mode 100644
index 0000000000..b25bcf139b
--- /dev/null
+++ b/t/helper/test-read-cache.c
@@ -0,0 +1,13 @@
+#include "cache.h"
+
+int main (int argc, char **argv)
+{
+	int i, cnt = 1;
+	if (argc == 2)
+		cnt = strtol(argv[1], NULL, 0);
+	for (i = 0; i < cnt; i++) {
+		read_cache();
+		discard_cache();
+	}
+	return 0;
+}
diff --git a/t/helper/test-regex.c b/t/helper/test-regex.c
new file mode 100644
index 0000000000..0dc598ecdc
--- /dev/null
+++ b/t/helper/test-regex.c
@@ -0,0 +1,20 @@
+#include "git-compat-util.h"
+
+int main(int argc, char **argv)
+{
+	char *pat = "[^={} \t]+";
+	char *str = "={}\nfred";
+	regex_t r;
+	regmatch_t m[1];
+
+	if (regcomp(&r, pat, REG_EXTENDED | REG_NEWLINE))
+		die("failed regcomp() for pattern '%s'", pat);
+	if (regexec(&r, str, 1, m, 0))
+		die("no match of pattern '%s' to string '%s'", pat, str);
+
+	/* http://sourceware.org/bugzilla/show_bug.cgi?id=3957  */
+	if (m[0].rm_so == 3) /* matches '\n' when it should not */
+		die("regex bug confirmed: re-build git with NO_REGEX=1");
+
+	exit(0);
+}
diff --git a/t/helper/test-revision-walking.c b/t/helper/test-revision-walking.c
new file mode 100644
index 0000000000..3d0313354b
--- /dev/null
+++ b/t/helper/test-revision-walking.c
@@ -0,0 +1,68 @@
+/*
+ * test-revision-walking.c: test revision walking API.
+ *
+ * (C) 2012 Heiko Voigt <hvoigt@hvoigt.net>
+ *
+ * This code is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "cache.h"
+#include "commit.h"
+#include "diff.h"
+#include "revision.h"
+
+static void print_commit(struct commit *commit)
+{
+	struct strbuf sb = STRBUF_INIT;
+	struct pretty_print_context ctx = {0};
+	ctx.date_mode.type = DATE_NORMAL;
+	format_commit_message(commit, " %m %s", &sb, &ctx);
+	printf("%s\n", sb.buf);
+	strbuf_release(&sb);
+}
+
+static int run_revision_walk(void)
+{
+	struct rev_info rev;
+	struct commit *commit;
+	const char *argv[] = {NULL, "--all", NULL};
+	int argc = ARRAY_SIZE(argv) - 1;
+	int got_revision = 0;
+
+	init_revisions(&rev, NULL);
+	setup_revisions(argc, argv, &rev, NULL);
+	if (prepare_revision_walk(&rev))
+		die("revision walk setup failed");
+
+	while ((commit = get_revision(&rev)) != NULL) {
+		print_commit(commit);
+		got_revision = 1;
+	}
+
+	reset_revision_walk();
+	return got_revision;
+}
+
+int main(int argc, char **argv)
+{
+	if (argc < 2)
+		return 1;
+
+	setup_git_directory();
+
+	if (!strcmp(argv[1], "run-twice")) {
+		printf("1st\n");
+		if (!run_revision_walk())
+			return 1;
+		printf("2nd\n");
+		if (!run_revision_walk())
+			return 1;
+
+		return 0;
+	}
+
+	fprintf(stderr, "check usage\n");
+	return 1;
+}
diff --git a/t/helper/test-run-command.c b/t/helper/test-run-command.c
new file mode 100644
index 0000000000..30a64a98dc
--- /dev/null
+++ b/t/helper/test-run-command.c
@@ -0,0 +1,87 @@
+/*
+ * test-run-command.c: test run command API.
+ *
+ * (C) 2009 Ilari Liusvaara <ilari.liusvaara@elisanet.fi>
+ *
+ * This code is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "git-compat-util.h"
+#include "run-command.h"
+#include "argv-array.h"
+#include "strbuf.h"
+#include <string.h>
+#include <errno.h>
+
+static int number_callbacks;
+static int parallel_next(struct child_process *cp,
+			 struct strbuf *err,
+			 void *cb,
+			 void **task_cb)
+{
+	struct child_process *d = cb;
+	if (number_callbacks >= 4)
+		return 0;
+
+	argv_array_pushv(&cp->args, d->argv);
+	strbuf_addf(err, "preloaded output of a child\n");
+	number_callbacks++;
+	return 1;
+}
+
+static int no_job(struct child_process *cp,
+		  struct strbuf *err,
+		  void *cb,
+		  void **task_cb)
+{
+	strbuf_addf(err, "no further jobs available\n");
+	return 0;
+}
+
+static int task_finished(int result,
+			 struct strbuf *err,
+			 void *pp_cb,
+			 void *pp_task_cb)
+{
+	strbuf_addf(err, "asking for a quick stop\n");
+	return 1;
+}
+
+int main(int argc, char **argv)
+{
+	struct child_process proc = CHILD_PROCESS_INIT;
+	int jobs;
+
+	if (argc < 3)
+		return 1;
+	proc.argv = (const char **)argv + 2;
+
+	if (!strcmp(argv[1], "start-command-ENOENT")) {
+		if (start_command(&proc) < 0 && errno == ENOENT)
+			return 0;
+		fprintf(stderr, "FAIL %s\n", argv[1]);
+		return 1;
+	}
+	if (!strcmp(argv[1], "run-command"))
+		exit(run_command(&proc));
+
+	jobs = atoi(argv[2]);
+	proc.argv = (const char **)argv + 3;
+
+	if (!strcmp(argv[1], "run-command-parallel"))
+		exit(run_processes_parallel(jobs, parallel_next,
+					    NULL, NULL, &proc));
+
+	if (!strcmp(argv[1], "run-command-abort"))
+		exit(run_processes_parallel(jobs, parallel_next,
+					    NULL, task_finished, &proc));
+
+	if (!strcmp(argv[1], "run-command-no-jobs"))
+		exit(run_processes_parallel(jobs, no_job,
+					    NULL, task_finished, &proc));
+
+	fprintf(stderr, "check usage\n");
+	return 1;
+}
diff --git a/t/helper/test-scrap-cache-tree.c b/t/helper/test-scrap-cache-tree.c
new file mode 100644
index 0000000000..6efee31a48
--- /dev/null
+++ b/t/helper/test-scrap-cache-tree.c
@@ -0,0 +1,17 @@
+#include "cache.h"
+#include "lockfile.h"
+#include "tree.h"
+#include "cache-tree.h"
+
+static struct lock_file index_lock;
+
+int main(int ac, char **av)
+{
+	hold_locked_index(&index_lock, 1);
+	if (read_cache() < 0)
+		die("unable to read index file");
+	active_cache_tree = NULL;
+	if (write_locked_index(&the_index, &index_lock, COMMIT_LOCK))
+		die("unable to write index file");
+	return 0;
+}
diff --git a/t/helper/test-sha1-array.c b/t/helper/test-sha1-array.c
new file mode 100644
index 0000000000..60ea1d5f14
--- /dev/null
+++ b/t/helper/test-sha1-array.c
@@ -0,0 +1,34 @@
+#include "cache.h"
+#include "sha1-array.h"
+
+static void print_sha1(const unsigned char sha1[20], void *data)
+{
+	puts(sha1_to_hex(sha1));
+}
+
+int main(int argc, char **argv)
+{
+	struct sha1_array array = SHA1_ARRAY_INIT;
+	struct strbuf line = STRBUF_INIT;
+
+	while (strbuf_getline(&line, stdin) != EOF) {
+		const char *arg;
+		unsigned char sha1[20];
+
+		if (skip_prefix(line.buf, "append ", &arg)) {
+			if (get_sha1_hex(arg, sha1))
+				die("not a hexadecimal SHA1: %s", arg);
+			sha1_array_append(&array, sha1);
+		} else if (skip_prefix(line.buf, "lookup ", &arg)) {
+			if (get_sha1_hex(arg, sha1))
+				die("not a hexadecimal SHA1: %s", arg);
+			printf("%d\n", sha1_array_lookup(&array, sha1));
+		} else if (!strcmp(line.buf, "clear"))
+			sha1_array_clear(&array);
+		else if (!strcmp(line.buf, "for_each_unique"))
+			sha1_array_for_each_unique(&array, print_sha1, NULL);
+		else
+			die("unknown command: %s", line.buf);
+	}
+	return 0;
+}
diff --git a/t/helper/test-sha1.c b/t/helper/test-sha1.c
new file mode 100644
index 0000000000..e57eae10bf
--- /dev/null
+++ b/t/helper/test-sha1.c
@@ -0,0 +1,56 @@
+#include "cache.h"
+
+int main(int ac, char **av)
+{
+	git_SHA_CTX ctx;
+	unsigned char sha1[20];
+	unsigned bufsz = 8192;
+	int binary = 0;
+	char *buffer;
+
+	if (ac == 2) {
+		if (!strcmp(av[1], "-b"))
+			binary = 1;
+		else
+			bufsz = strtoul(av[1], NULL, 10) * 1024 * 1024;
+	}
+
+	if (!bufsz)
+		bufsz = 8192;
+
+	while ((buffer = malloc(bufsz)) == NULL) {
+		fprintf(stderr, "bufsz %u is too big, halving...\n", bufsz);
+		bufsz /= 2;
+		if (bufsz < 1024)
+			die("OOPS");
+	}
+
+	git_SHA1_Init(&ctx);
+
+	while (1) {
+		ssize_t sz, this_sz;
+		char *cp = buffer;
+		unsigned room = bufsz;
+		this_sz = 0;
+		while (room) {
+			sz = xread(0, cp, room);
+			if (sz == 0)
+				break;
+			if (sz < 0)
+				die_errno("test-sha1");
+			this_sz += sz;
+			cp += sz;
+			room -= sz;
+		}
+		if (this_sz == 0)
+			break;
+		git_SHA1_Update(&ctx, buffer, this_sz);
+	}
+	git_SHA1_Final(sha1, &ctx);
+
+	if (binary)
+		fwrite(sha1, 1, 20, stdout);
+	else
+		puts(sha1_to_hex(sha1));
+	exit(0);
+}
diff --git a/t/helper/test-sha1.sh b/t/helper/test-sha1.sh
new file mode 100755
index 0000000000..750b95a0a1
--- /dev/null
+++ b/t/helper/test-sha1.sh
@@ -0,0 +1,83 @@
+#!/bin/sh
+
+dd if=/dev/zero bs=1048576 count=100 2>/dev/null |
+/usr/bin/time t/helper/test-sha1 >/dev/null
+
+while read expect cnt pfx
+do
+	case "$expect" in '#'*) continue ;; esac
+	actual=$(
+		{
+			test -z "$pfx" || echo "$pfx"
+			dd if=/dev/zero bs=1048576 count=$cnt 2>/dev/null |
+			perl -pe 'y/\000/g/'
+		} | ./t/helper/test-sha1 $cnt
+	)
+	if test "$expect" = "$actual"
+	then
+		echo "OK: $expect $cnt $pfx"
+	else
+		echo >&2 "OOPS: $cnt"
+		echo >&2 "expect: $expect"
+		echo >&2 "actual: $actual"
+		exit 1
+	fi
+done <<EOF
+da39a3ee5e6b4b0d3255bfef95601890afd80709 0
+3f786850e387550fdab836ed7e6dc881de23001b 0 a
+5277cbb45a15902137d332d97e89cf8136545485 0 ab
+03cfd743661f07975fa2f1220c5194cbaff48451 0 abc
+3330b4373640f9e4604991e73c7e86bfd8da2dc3 0 abcd
+ec11312386ad561674f724b8cca7cf1796e26d1d 0 abcde
+bdc37c074ec4ee6050d68bc133c6b912f36474df 0 abcdef
+69bca99b923859f2dc486b55b87f49689b7358c7 0 abcdefg
+e414af7161c9554089f4106d6f1797ef14a73666 0 abcdefgh
+0707f2970043f9f7c22029482db27733deaec029 0 abcdefghi
+a4dd8aa74a5636728fe52451636e2e17726033aa 1
+9986b45e2f4d7086372533bb6953a8652fa3644a 1 frotz
+23d8d4f788e8526b4877548a32577543cbaaf51f 10
+8cd23f822ab44c7f481b8c92d591f6d1fcad431c 10 frotz
+f3b5604a4e604899c1233edb3bf1cc0ede4d8c32 512
+b095bd837a371593048136e429e9ac4b476e1bb3 512 frotz
+08fa81d6190948de5ccca3966340cc48c10cceac 1200 xyzzy
+e33a291f42c30a159733dd98b8b3e4ff34158ca0 4090 4G
+#a3bf783bc20caa958f6cb24dd140a7b21984838d 9999 nitfol
+EOF
+
+exit
+
+# generating test vectors
+# inputs are number of megabytes followed by some random string to prefix.
+
+while read cnt pfx
+do
+	actual=$(
+		{
+			test -z "$pfx" || echo "$pfx"
+			dd if=/dev/zero bs=1048576 count=$cnt 2>/dev/null |
+			perl -pe 'y/\000/g/'
+		} | sha1sum |
+		sed -e 's/ .*//'
+	)
+	echo "$actual $cnt $pfx"
+done <<EOF
+0
+0 a
+0 ab
+0 abc
+0 abcd
+0 abcde
+0 abcdef
+0 abcdefg
+0 abcdefgh
+0 abcdefghi
+1
+1 frotz
+10
+10 frotz
+512
+512 frotz
+1200 xyzzy
+4090 4G
+9999 nitfol
+EOF
diff --git a/t/helper/test-sigchain.c b/t/helper/test-sigchain.c
new file mode 100644
index 0000000000..e499fce60f
--- /dev/null
+++ b/t/helper/test-sigchain.c
@@ -0,0 +1,22 @@
+#include "cache.h"
+#include "sigchain.h"
+
+#define X(f) \
+static void f(int sig) { \
+	puts(#f); \
+	fflush(stdout); \
+	sigchain_pop(sig); \
+	raise(sig); \
+}
+X(one)
+X(two)
+X(three)
+#undef X
+
+int main(int argc, char **argv) {
+	sigchain_push(SIGTERM, one);
+	sigchain_push(SIGTERM, two);
+	sigchain_push(SIGTERM, three);
+	raise(SIGTERM);
+	return 0;
+}
diff --git a/t/helper/test-string-list.c b/t/helper/test-string-list.c
new file mode 100644
index 0000000000..14bdf9d215
--- /dev/null
+++ b/t/helper/test-string-list.c
@@ -0,0 +1,103 @@
+#include "cache.h"
+#include "string-list.h"
+
+/*
+ * Parse an argument into a string list.  arg should either be a
+ * ':'-separated list of strings, or "-" to indicate an empty string
+ * list (as opposed to "", which indicates a string list containing a
+ * single empty string).  list->strdup_strings must be set.
+ */
+static void parse_string_list(struct string_list *list, const char *arg)
+{
+	if (!strcmp(arg, "-"))
+		return;
+
+	(void)string_list_split(list, arg, ':', -1);
+}
+
+static void write_list(const struct string_list *list)
+{
+	int i;
+	for (i = 0; i < list->nr; i++)
+		printf("[%d]: \"%s\"\n", i, list->items[i].string);
+}
+
+static void write_list_compact(const struct string_list *list)
+{
+	int i;
+	if (!list->nr)
+		printf("-\n");
+	else {
+		printf("%s", list->items[0].string);
+		for (i = 1; i < list->nr; i++)
+			printf(":%s", list->items[i].string);
+		printf("\n");
+	}
+}
+
+static int prefix_cb(struct string_list_item *item, void *cb_data)
+{
+	const char *prefix = (const char *)cb_data;
+	return starts_with(item->string, prefix);
+}
+
+int main(int argc, char **argv)
+{
+	if (argc == 5 && !strcmp(argv[1], "split")) {
+		struct string_list list = STRING_LIST_INIT_DUP;
+		int i;
+		const char *s = argv[2];
+		int delim = *argv[3];
+		int maxsplit = atoi(argv[4]);
+
+		i = string_list_split(&list, s, delim, maxsplit);
+		printf("%d\n", i);
+		write_list(&list);
+		string_list_clear(&list, 0);
+		return 0;
+	}
+
+	if (argc == 5 && !strcmp(argv[1], "split_in_place")) {
+		struct string_list list = STRING_LIST_INIT_NODUP;
+		int i;
+		char *s = xstrdup(argv[2]);
+		int delim = *argv[3];
+		int maxsplit = atoi(argv[4]);
+
+		i = string_list_split_in_place(&list, s, delim, maxsplit);
+		printf("%d\n", i);
+		write_list(&list);
+		string_list_clear(&list, 0);
+		free(s);
+		return 0;
+	}
+
+	if (argc == 4 && !strcmp(argv[1], "filter")) {
+		/*
+		 * Retain only the items that have the specified prefix.
+		 * Arguments: list|- prefix
+		 */
+		struct string_list list = STRING_LIST_INIT_DUP;
+		const char *prefix = argv[3];
+
+		parse_string_list(&list, argv[2]);
+		filter_string_list(&list, 0, prefix_cb, (void *)prefix);
+		write_list_compact(&list);
+		string_list_clear(&list, 0);
+		return 0;
+	}
+
+	if (argc == 3 && !strcmp(argv[1], "remove_duplicates")) {
+		struct string_list list = STRING_LIST_INIT_DUP;
+
+		parse_string_list(&list, argv[2]);
+		string_list_remove_duplicates(&list, 0);
+		write_list_compact(&list);
+		string_list_clear(&list, 0);
+		return 0;
+	}
+
+	fprintf(stderr, "%s: unknown function name: %s\n", argv[0],
+		argv[1] ? argv[1] : "(there was none)");
+	return 1;
+}
diff --git a/t/helper/test-submodule-config.c b/t/helper/test-submodule-config.c
new file mode 100644
index 0000000000..dab8c27768
--- /dev/null
+++ b/t/helper/test-submodule-config.c
@@ -0,0 +1,76 @@
+#include "cache.h"
+#include "submodule-config.h"
+#include "submodule.h"
+
+static void die_usage(int argc, char **argv, const char *msg)
+{
+	fprintf(stderr, "%s\n", msg);
+	fprintf(stderr, "Usage: %s [<commit> <submodulepath>] ...\n", argv[0]);
+	exit(1);
+}
+
+static int git_test_config(const char *var, const char *value, void *cb)
+{
+	return parse_submodule_config_option(var, value);
+}
+
+int main(int argc, char **argv)
+{
+	char **arg = argv;
+	int my_argc = argc;
+	int output_url = 0;
+	int lookup_name = 0;
+
+	arg++;
+	my_argc--;
+	while (starts_with(arg[0], "--")) {
+		if (!strcmp(arg[0], "--url"))
+			output_url = 1;
+		if (!strcmp(arg[0], "--name"))
+			lookup_name = 1;
+		arg++;
+		my_argc--;
+	}
+
+	if (my_argc % 2 != 0)
+		die_usage(argc, argv, "Wrong number of arguments.");
+
+	setup_git_directory();
+	gitmodules_config();
+	git_config(git_test_config, NULL);
+
+	while (*arg) {
+		unsigned char commit_sha1[20];
+		const struct submodule *submodule;
+		const char *commit;
+		const char *path_or_name;
+
+		commit = arg[0];
+		path_or_name = arg[1];
+
+		if (commit[0] == '\0')
+			hashcpy(commit_sha1, null_sha1);
+		else if (get_sha1(commit, commit_sha1) < 0)
+			die_usage(argc, argv, "Commit not found.");
+
+		if (lookup_name) {
+			submodule = submodule_from_name(commit_sha1, path_or_name);
+		} else
+			submodule = submodule_from_path(commit_sha1, path_or_name);
+		if (!submodule)
+			die_usage(argc, argv, "Submodule not found.");
+
+		if (output_url)
+			printf("Submodule url: '%s' for path '%s'\n",
+					submodule->url, submodule->path);
+		else
+			printf("Submodule name: '%s' for path '%s'\n",
+					submodule->name, submodule->path);
+
+		arg += 2;
+	}
+
+	submodule_free();
+
+	return 0;
+}
diff --git a/t/helper/test-subprocess.c b/t/helper/test-subprocess.c
new file mode 100644
index 0000000000..56881a0324
--- /dev/null
+++ b/t/helper/test-subprocess.c
@@ -0,0 +1,19 @@
+#include "cache.h"
+#include "run-command.h"
+
+int main(int argc, char **argv)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+	int nogit = 0;
+
+	setup_git_directory_gently(&nogit);
+	if (nogit)
+		die("No git repo found");
+	if (argc > 1 && !strcmp(argv[1], "--setup-work-tree")) {
+		setup_work_tree();
+		argv++;
+	}
+	cp.git_cmd = 1;
+	cp.argv = (const char **)argv + 1;
+	return run_command(&cp);
+}
diff --git a/t/helper/test-svn-fe.c b/t/helper/test-svn-fe.c
new file mode 100644
index 0000000000..120ec96b0d
--- /dev/null
+++ b/t/helper/test-svn-fe.c
@@ -0,0 +1,52 @@
+/*
+ * test-svn-fe: Code to exercise the svn import lib
+ */
+
+#include "git-compat-util.h"
+#include "vcs-svn/svndump.h"
+#include "vcs-svn/svndiff.h"
+#include "vcs-svn/sliding_window.h"
+#include "vcs-svn/line_buffer.h"
+
+static const char test_svnfe_usage[] =
+	"test-svn-fe (<dumpfile> | [-d] <preimage> <delta> <len>)";
+
+static int apply_delta(int argc, char *argv[])
+{
+	struct line_buffer preimage = LINE_BUFFER_INIT;
+	struct line_buffer delta = LINE_BUFFER_INIT;
+	struct sliding_view preimage_view = SLIDING_VIEW_INIT(&preimage, -1);
+
+	if (argc != 5)
+		usage(test_svnfe_usage);
+
+	if (buffer_init(&preimage, argv[2]))
+		die_errno("cannot open preimage");
+	if (buffer_init(&delta, argv[3]))
+		die_errno("cannot open delta");
+	if (svndiff0_apply(&delta, (off_t) strtoumax(argv[4], NULL, 0),
+					&preimage_view, stdout))
+		return 1;
+	if (buffer_deinit(&preimage))
+		die_errno("cannot close preimage");
+	if (buffer_deinit(&delta))
+		die_errno("cannot close delta");
+	strbuf_release(&preimage_view.buf);
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	if (argc == 2) {
+		if (svndump_init(argv[1]))
+			return 1;
+		svndump_read(NULL, "refs/heads/master", "refs/notes/svn/revs");
+		svndump_deinit();
+		svndump_reset();
+		return 0;
+	}
+
+	if (argc >= 2 && !strcmp(argv[1], "-d"))
+		return apply_delta(argc, argv);
+	usage(test_svnfe_usage);
+}
diff --git a/t/helper/test-urlmatch-normalization.c b/t/helper/test-urlmatch-normalization.c
new file mode 100644
index 0000000000..090bf219a7
--- /dev/null
+++ b/t/helper/test-urlmatch-normalization.c
@@ -0,0 +1,50 @@
+#include "git-compat-util.h"
+#include "urlmatch.h"
+
+int main(int argc, char **argv)
+{
+	const char usage[] = "test-urlmatch-normalization [-p | -l] <url1> | <url1> <url2>";
+	char *url1, *url2;
+	int opt_p = 0, opt_l = 0;
+
+	/*
+	 * For one url, succeed if url_normalize succeeds on it, fail otherwise.
+	 * For two urls, succeed only if url_normalize succeeds on both and
+	 * the results compare equal with strcmp.  If -p is given (one url only)
+	 * and url_normalize succeeds, print the result followed by "\n".  If
+	 * -l is given (one url only) and url_normalize succeeds, print the
+	 * returned length in decimal followed by "\n".
+	 */
+
+	if (argc > 1 && !strcmp(argv[1], "-p")) {
+		opt_p = 1;
+		argc--;
+		argv++;
+	} else if (argc > 1 && !strcmp(argv[1], "-l")) {
+		opt_l = 1;
+		argc--;
+		argv++;
+	}
+
+	if (argc < 2 || argc > 3)
+		die("%s", usage);
+
+	if (argc == 2) {
+		struct url_info info;
+		url1 = url_normalize(argv[1], &info);
+		if (!url1)
+			return 1;
+		if (opt_p)
+			printf("%s\n", url1);
+		if (opt_l)
+			printf("%u\n", (unsigned)info.url_len);
+		return 0;
+	}
+
+	if (opt_p || opt_l)
+		die("%s", usage);
+
+	url1 = url_normalize(argv[1], NULL);
+	url2 = url_normalize(argv[2], NULL);
+	return (url1 && url2 && !strcmp(url1, url2)) ? 0 : 1;
+}
diff --git a/t/helper/test-wildmatch.c b/t/helper/test-wildmatch.c
new file mode 100644
index 0000000000..578b164fe6
--- /dev/null
+++ b/t/helper/test-wildmatch.c
@@ -0,0 +1,21 @@
+#include "cache.h"
+
+int main(int argc, char **argv)
+{
+	int i;
+	for (i = 2; i < argc; i++) {
+		if (argv[i][0] == '/')
+			die("Forward slash is not allowed at the beginning of the\n"
+			    "pattern because Windows does not like it. Use `XXX/' instead.");
+		else if (!strncmp(argv[i], "XXX/", 4))
+			argv[i] += 3;
+	}
+	if (!strcmp(argv[1], "wildmatch"))
+		return !!wildmatch(argv[3], argv[2], WM_PATHNAME, NULL);
+	else if (!strcmp(argv[1], "iwildmatch"))
+		return !!wildmatch(argv[3], argv[2], WM_PATHNAME | WM_CASEFOLD, NULL);
+	else if (!strcmp(argv[1], "pathmatch"))
+		return !!wildmatch(argv[3], argv[2], 0, NULL);
+	else
+		return 1;
+}