feat: add cache package for exclude list and health cache YAML read/write

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/cache/cache_test.go

@@ -0,0 +1,105 @@
+package cache
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+)
+
+func TestLoadExcludeList(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "exclude.yaml")
+	content := `domains:
+  - https://example.com
+  - https://test.org
+`
+	if err := os.WriteFile(path, []byte(content), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	excl, err := LoadExcludeList(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(excl.Domains) != 2 {
+		t.Errorf("domains count = %d, want 2", len(excl.Domains))
+	}
+	if !excl.IsExcluded("https://example.com/foo") {
+		t.Error("expected https://example.com/foo to be excluded")
+	}
+	if excl.IsExcluded("https://other.com") {
+		t.Error("expected https://other.com to NOT be excluded")
+	}
+}
+
+func TestHealthCacheRoundTrip(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "health.yaml")
+
+	original := &HealthCache{
+		Entries: []HealthEntry{
+			{
+				URL:        "https://github.com/example/repo",
+				Name:       "Example",
+				Status:     "healthy",
+				Stars:      42,
+				LastPush:   time.Date(2026, 1, 15, 0, 0, 0, 0, time.UTC),
+				HasLicense: true,
+				HasReadme:  true,
+				CheckedAt:  time.Date(2026, 2, 27, 9, 0, 0, 0, time.UTC),
+			},
+		},
+	}
+
+	if err := SaveHealthCache(path, original); err != nil {
+		t.Fatal(err)
+	}
+
+	loaded, err := LoadHealthCache(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(loaded.Entries) != 1 {
+		t.Fatalf("entries = %d, want 1", len(loaded.Entries))
+	}
+	if loaded.Entries[0].Stars != 42 {
+		t.Errorf("stars = %d, want 42", loaded.Entries[0].Stars)
+	}
+}
+
+func TestLoadHealthCacheMissing(t *testing.T) {
+	hc, err := LoadHealthCache("/nonexistent/path.yaml")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(hc.Entries) != 0 {
+		t.Errorf("entries = %d, want 0 for missing file", len(hc.Entries))
+	}
+}
+
+func TestMerge(t *testing.T) {
+	hc := &HealthCache{
+		Entries: []HealthEntry{
+			{URL: "https://github.com/a/a", Name: "A", Stars: 10},
+			{URL: "https://github.com/b/b", Name: "B", Stars: 20},
+		},
+	}
+
+	hc.Merge([]HealthEntry{
+		{URL: "https://github.com/b/b", Name: "B", Stars: 25}, // update
+		{URL: "https://github.com/c/c", Name: "C", Stars: 30}, // new
+	})
+
+	if len(hc.Entries) != 3 {
+		t.Fatalf("entries = %d, want 3", len(hc.Entries))
+	}
+	// B should be updated
+	if hc.Entries[1].Stars != 25 {
+		t.Errorf("B stars = %d, want 25", hc.Entries[1].Stars)
+	}
+	// C should be appended
+	if hc.Entries[2].Name != "C" {
+		t.Errorf("last entry = %q, want C", hc.Entries[2].Name)
+	}
+}