1 files changed, 298 insertions, 0 deletions
diff --git a/internal/paging/page_test.go b/internal/paging/page_test.go
new file mode 100644
index 000000000..419b9ea44
--- /dev/null
+++ b/internal/paging/page_test.go
@@ -0,0 +1,298 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package paging_test
+
+import (
+	"math/rand"
+	"testing"
+	"time"
+
+	"github.com/oklog/ulid"
+	"github.com/superseriousbusiness/gotosocial/internal/paging"
+	"golang.org/x/exp/slices"
+)
+
+// random reader according to current-time source seed.
+var randRd = rand.New(rand.NewSource(time.Now().Unix()))
+
+type Case struct {
+	// Name is the test case name.
+	Name string
+
+	// Page to use for test.
+	Page *paging.Page
+
+	// Input contains test case input ID slice.
+	Input []string
+
+	// Expect contains expected test case output.
+	Expect []string
+}
+
+// CreateCase creates a new test case with random input for function defining test page parameters and expected output.
+func CreateCase(name string, getParams func([]string) (input []string, page *paging.Page, expect []string)) Case {
+	i := randRd.Intn(100)
+	in := generateSlice(i)
+	input, page, expect := getParams(in)
+	return Case{
+		Name:   name,
+		Page:   page,
+		Input:  input,
+		Expect: expect,
+	}
+}
+
+func TestPage(t *testing.T) {
+	for _, c := range cases {
+		t.Run(c.Name, func(t *testing.T) {
+			// Page the input slice.
+			out := c.Page.Page(c.Input)
+
+			// Log the results for case of error returns.
+			t.Logf("\ninput=%v\noutput=%v\nexpected=%v", c.Input, out, c.Expect)
+
+			// Check paged output is as expected.
+			if !slices.Equal(out, c.Expect) {
+				t.Error("unexpected paged output")
+			}
+		})
+	}
+}
+
+var cases = []Case{
+	CreateCase("minID and maxID set", func(ids []string) ([]string, *paging.Page, []string) {
+		// Ensure input slice sorted ascending for min_id
+		slices.SortFunc(ids, func(a, b string) bool {
+			return a > b // i.e. largest at lowest idx
+		})
+
+		// Select random indices in slice.
+		minIdx := randRd.Intn(len(ids))
+		maxIdx := randRd.Intn(len(ids))
+
+		// Select the boundaries.
+		minID := ids[minIdx]
+		maxID := ids[maxIdx]
+
+		// Create expected output.
+		expect := slices.Clone(ids)
+		expect = cutLower(expect, minID)
+		expect = cutUpper(expect, maxID)
+		expect = paging.Reverse(expect)
+
+		// Return page and expected IDs.
+		return ids, &paging.Page{
+			Min: paging.MinID(minID, ""),
+			Max: paging.MaxID(maxID),
+		}, expect
+	}),
+	CreateCase("minID, maxID and limit set", func(ids []string) ([]string, *paging.Page, []string) {
+		// Ensure input slice sorted ascending for min_id
+		slices.SortFunc(ids, func(a, b string) bool {
+			return a > b // i.e. largest at lowest idx
+		})
+
+		// Select random parameters in slice.
+		minIdx := randRd.Intn(len(ids))
+		maxIdx := randRd.Intn(len(ids))
+		limit := randRd.Intn(len(ids))
+
+		// Select the boundaries.
+		minID := ids[minIdx]
+		maxID := ids[maxIdx]
+
+		// Create expected output.
+		expect := slices.Clone(ids)
+		expect = cutLower(expect, minID)
+		expect = cutUpper(expect, maxID)
+		expect = paging.Reverse(expect)
+
+		// Now limit the slice.
+		if limit < len(expect) {
+			expect = expect[:limit]
+		}
+
+		// Return page and expected IDs.
+		return ids, &paging.Page{
+			Min:   paging.MinID(minID, ""),
+			Max:   paging.MaxID(maxID),
+			Limit: limit,
+		}, expect
+	}),
+	CreateCase("minID, maxID and too-large limit set", func(ids []string) ([]string, *paging.Page, []string) {
+		// Ensure input slice sorted ascending for min_id
+		slices.SortFunc(ids, func(a, b string) bool {
+			return a > b // i.e. largest at lowest idx
+		})
+
+		// Select random parameters in slice.
+		minIdx := randRd.Intn(len(ids))
+		maxIdx := randRd.Intn(len(ids))
+
+		// Select the boundaries.
+		minID := ids[minIdx]
+		maxID := ids[maxIdx]
+
+		// Create expected output.
+		expect := slices.Clone(ids)
+		expect = cutLower(expect, minID)
+		expect = cutUpper(expect, maxID)
+		expect = paging.Reverse(expect)
+
+		// Return page and expected IDs.
+		return ids, &paging.Page{
+			Min:   paging.MinID(minID, ""),
+			Max:   paging.MaxID(maxID),
+			Limit: len(ids) * 2,
+		}, expect
+	}),
+	CreateCase("sinceID and maxID set", func(ids []string) ([]string, *paging.Page, []string) {
+		// Ensure input slice sorted descending for since_id
+		slices.SortFunc(ids, func(a, b string) bool {
+			return a < b // i.e. smallest at lowest idx
+		})
+
+		// Select random indices in slice.
+		sinceIdx := randRd.Intn(len(ids))
+		maxIdx := randRd.Intn(len(ids))
+
+		// Select the boundaries.
+		sinceID := ids[sinceIdx]
+		maxID := ids[maxIdx]
+
+		// Create expected output.
+		expect := slices.Clone(ids)
+		expect = cutLower(expect, maxID)
+		expect = cutUpper(expect, sinceID)
+
+		// Return page and expected IDs.
+		return ids, &paging.Page{
+			Min: paging.MinID("", sinceID),
+			Max: paging.MaxID(maxID),
+		}, expect
+	}),
+	CreateCase("maxID set", func(ids []string) ([]string, *paging.Page, []string) {
+		// Ensure input slice sorted descending for max_id
+		slices.SortFunc(ids, func(a, b string) bool {
+			return a < b // i.e. smallest at lowest idx
+		})
+
+		// Select random indices in slice.
+		maxIdx := randRd.Intn(len(ids))
+
+		// Select the boundaries.
+		maxID := ids[maxIdx]
+
+		// Create expected output.
+		expect := slices.Clone(ids)
+		expect = cutLower(expect, maxID)
+
+		// Return page and expected IDs.
+		return ids, &paging.Page{
+			Max: paging.MaxID(maxID),
+		}, expect
+	}),
+	CreateCase("sinceID set", func(ids []string) ([]string, *paging.Page, []string) {
+		// Ensure input slice sorted descending for since_id
+		slices.SortFunc(ids, func(a, b string) bool {
+			return a < b
+		})
+
+		// Select random indices in slice.
+		sinceIdx := randRd.Intn(len(ids))
+
+		// Select the boundaries.
+		sinceID := ids[sinceIdx]
+
+		// Create expected output.
+		expect := slices.Clone(ids)
+		expect = cutUpper(expect, sinceID)
+
+		// Return page and expected IDs.
+		return ids, &paging.Page{
+			Min: paging.MinID("", sinceID),
+		}, expect
+	}),
+	CreateCase("minID set", func(ids []string) ([]string, *paging.Page, []string) {
+		// Ensure input slice sorted ascending for min_id
+		slices.SortFunc(ids, func(a, b string) bool {
+			return a > b // i.e. largest at lowest idx
+		})
+
+		// Select random indices in slice.
+		minIdx := randRd.Intn(len(ids))
+
+		// Select the boundaries.
+		minID := ids[minIdx]
+
+		// Create expected output.
+		expect := slices.Clone(ids)
+		expect = cutLower(expect, minID)
+		expect = paging.Reverse(expect)
+
+		// Return page and expected IDs.
+		return ids, &paging.Page{
+			Min: paging.MinID(minID, ""),
+		}, expect
+	}),
+}
+
+// cutLower cuts off the lower part of the slice from `bound` downwards.
+func cutLower(in []string, bound string) []string {
+	for i := 0; i < len(in); i++ {
+		if in[i] == bound {
+			return in[i+1:]
+		}
+	}
+	return in
+}
+
+// cutUpper cuts off the upper part of the slice from `bound` onwards.
+func cutUpper(in []string, bound string) []string {
+	for i := 0; i < len(in); i++ {
+		if in[i] == bound {
+			return in[:i]
+		}
+	}
+	return in
+}
+
+// generateSlice generates a new slice of len containing ascending sorted slice.
+func generateSlice(len int) []string {
+	if len <= 0 {
+		// minimum testable
+		// pageable amount
+		len = 2
+	}
+	now := time.Now()
+	in := make([]string, len)
+	for i := 0; i < len; i++ {
+		// Convert now to timestamp.
+		t := ulid.Timestamp(now)
+
+		// Create anew ulid for now.
+		u := ulid.MustNew(t, randRd)
+
+		// Add to slice.
+		in[i] = u.String()
+
+		// Bump now by 1 second.
+		now = now.Add(time.Second)
+	}
+	return in
+}