1 files changed, 97 insertions, 0 deletions
diff --git a/t/t4020-diff-external.sh b/t/t4020-diff-external.sh
new file mode 100755
index 0000000000..f0045cd788
--- /dev/null
+++ b/t/t4020-diff-external.sh
@@ -0,0 +1,97 @@
+#!/bin/sh
+
+test_description='external diff interface test'
+
+. ./test-lib.sh
+
+_z40=0000000000000000000000000000000000000000
+
+test_expect_success setup '
+
+	test_tick &&
+	echo initial >file &&
+	git add file &&
+	git commit -m initial &&
+
+	test_tick &&
+	echo second >file &&
+	git add file &&
+	git commit -m second &&
+
+	test_tick &&
+	echo third >file
+'
+
+test_expect_success 'GIT_EXTERNAL_DIFF environment' '
+
+	GIT_EXTERNAL_DIFF=echo git diff | {
+		read path oldfile oldhex oldmode newfile newhex newmode &&
+		test "z$path" = zfile &&
+		test "z$oldmode" = z100644 &&
+		test "z$newhex" = "z$_z40" &&
+		test "z$newmode" = z100644 &&
+		oh=$(git rev-parse --verify HEAD:file) &&
+		test "z$oh" = "z$oldhex"
+	}
+
+'
+
+test_expect_success 'GIT_EXTERNAL_DIFF environment should apply only to diff' '
+
+	GIT_EXTERNAL_DIFF=echo git log -p -1 HEAD |
+	grep "^diff --git a/file b/file"
+
+'
+
+test_expect_success 'diff attribute' '
+
+	git config diff.parrot.command echo &&
+
+	echo >.gitattributes "file diff=parrot" &&
+
+	git diff | {
+		read path oldfile oldhex oldmode newfile newhex newmode &&
+		test "z$path" = zfile &&
+		test "z$oldmode" = z100644 &&
+		test "z$newhex" = "z$_z40" &&
+		test "z$newmode" = z100644 &&
+		oh=$(git rev-parse --verify HEAD:file) &&
+		test "z$oh" = "z$oldhex"
+	}
+
+'
+
+test_expect_success 'diff attribute should apply only to diff' '
+
+	git log -p -1 HEAD |
+	grep "^diff --git a/file b/file"
+
+'
+
+test_expect_success 'diff attribute' '
+
+	git config --unset diff.parrot.command &&
+	git config diff.color.command echo &&
+
+	echo >.gitattributes "file diff=color" &&
+
+	git diff | {
+		read path oldfile oldhex oldmode newfile newhex newmode &&
+		test "z$path" = zfile &&
+		test "z$oldmode" = z100644 &&
+		test "z$newhex" = "z$_z40" &&
+		test "z$newmode" = z100644 &&
+		oh=$(git rev-parse --verify HEAD:file) &&
+		test "z$oh" = "z$oldhex"
+	}
+
+'
+
+test_expect_success 'diff attribute should apply only to diff' '
+
+	git log -p -1 HEAD |
+	grep "^diff --git a/file b/file"
+
+'
+
+test_done