Initial GoWallpaper implementation

cache_test.go

@@ -0,0 +1,60 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestCacheHistoryAndTrim(t *testing.T) {
+	dir := t.TempDir()
+	idx, err := loadCacheIndex(dir)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, name := range []string{"one.jpg", "two.jpg", "three.jpg"} {
+		path := filepath.Join(dir, name)
+		if err := os.WriteFile(path, []byte(name), 0o644); err != nil {
+			t.Fatal(err)
+		}
+		if err := idx.add(path, 2); err != nil {
+			t.Fatal(err)
+		}
+	}
+	if len(idx.Entries) != 2 || idx.Entries[0].FileName != "two.jpg" || idx.Current != 1 {
+		t.Fatalf("unexpected trimmed index: %+v", idx)
+	}
+	if _, err := os.Stat(filepath.Join(dir, "one.jpg")); !os.IsNotExist(err) {
+		t.Fatal("oldest cached image was not removed")
+	}
+	path, moved, err := idx.previous()
+	if err != nil || !moved || filepath.Base(path) != "two.jpg" {
+		t.Fatalf("unexpected previous result: %q %v %v", path, moved, err)
+	}
+	if _, moved, err := idx.previous(); err != nil || moved {
+		t.Fatalf("expected oldest boundary, moved=%v err=%v", moved, err)
+	}
+	path, moved, err = idx.next()
+	if err != nil || !moved || filepath.Base(path) != "three.jpg" {
+		t.Fatalf("unexpected next result: %q %v %v", path, moved, err)
+	}
+}
+
+func TestCacheIndexRepairsMissingFiles(t *testing.T) {
+	dir := t.TempDir()
+	idx := &CacheIndex{
+		Entries:  []CacheEntry{{FileName: "missing.jpg"}},
+		Current:  0,
+		cacheDir: dir,
+	}
+	if err := idx.save(); err != nil {
+		t.Fatal(err)
+	}
+	loaded, err := loadCacheIndex(dir)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(loaded.Entries) != 0 || loaded.Current != -1 {
+		t.Fatalf("missing file was not repaired: %+v", loaded)
+	}
+}