internal/pkg: relocate cache test helper

This is useful for other tests that need a cache instance.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/pkg/pkg_test.go

@@ -17,6 +17,64 @@ import (
 	"hakurei.app/internal/pkg"
 )
 
+// cacheTestCase is a test case passed to checkWithCache where a new instance
+// of [pkg.Cache] is prepared for the test case, and is validated and removed
+// on test completion.
+type cacheTestCase struct {
+	name  string
+	early func(t *testing.T, base *check.Absolute)
+	f     func(t *testing.T, base *check.Absolute, c *pkg.Cache)
+	want  pkg.Checksum
+}
+
+// checkWithCache runs a slice of cacheTestCase.
+func checkWithCache(t *testing.T, testCases []cacheTestCase) {
+	t.Helper()
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			base := check.MustAbs(t.TempDir())
+			if err := os.Chmod(base.String(), 0700); err != nil {
+				t.Fatal(err)
+			}
+			t.Cleanup(func() {
+				if err := filepath.WalkDir(base.String(), func(path string, d fs.DirEntry, err error) error {
+					if err != nil {
+						t.Error(err)
+						return nil
+					}
+					if !d.IsDir() {
+						return nil
+					}
+					return os.Chmod(path, 0700)
+				}); err != nil {
+					t.Fatal(err)
+				}
+			})
+
+			if c, err := pkg.New(base); err != nil {
+				t.Fatalf("New: error = %v", err)
+			} else {
+				if tc.early != nil {
+					tc.early(t, base)
+				}
+				tc.f(t, base, c)
+			}
+
+			if checksum, err := pkg.HashDir(base); err != nil {
+				t.Fatalf("HashDir: error = %v", err)
+			} else if checksum != tc.want {
+				t.Fatalf("HashDir: %v", &pkg.ChecksumMismatchError{
+					Got:  checksum,
+					Want: tc.want,
+				})
+			}
+		})
+	}
+}
+
 func TestCache(t *testing.T) {
 	t.Parallel()
 
@@ -35,12 +93,7 @@ func TestCache(t *testing.T) {
 
 	testdataChecksumString := base64.URLEncoding.EncodeToString(testdataChecksum[:])
 
-	testCases := []struct {
-		name  string
-		early func(t *testing.T, base *check.Absolute)
-		f     func(t *testing.T, base *check.Absolute, c *pkg.Cache)
-		check func(t *testing.T, base *check.Absolute)
-	}{
+	testCases := []cacheTestCase{
 		{"file", nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
 			wantErrNonexistent := &os.PathError{
 				Op: "open",
@@ -209,54 +262,9 @@ func TestCache(t *testing.T) {
 			if _, _, err := c.LoadFile(zeroIdent); !reflect.DeepEqual(err, wantErrNonexistentZero) {
 				t.Fatalf("LoadFile: error = %#v, want %#v", err, wantErrNonexistentZero)
 			}
-		}, func(t *testing.T, base *check.Absolute) {
-			wantChecksum := pkg.MustDecode(
-				"ZNSQH-mjhtIbFvi51lQ0UjatjoS8_5ILrBPNWlO2LWTq9P6MJEnekYzP0esUJnVr",
-			)
-			if checksum, err := pkg.HashDir(base); err != nil {
-				t.Fatalf("HashDir: error = %v", err)
-			} else if checksum != wantChecksum {
-				t.Fatalf("HashDir: %v", &pkg.ChecksumMismatchError{
-					Got:  checksum,
-					Want: wantChecksum,
-				})
-			}
-		}},
-	}
-	for _, tc := range testCases {
-		t.Run(tc.name, func(t *testing.T) {
-			t.Parallel()
-
-			base := check.MustAbs(t.TempDir())
-			if err := os.Chmod(base.String(), 0700); err != nil {
-				t.Fatal(err)
-			}
-			t.Cleanup(func() {
-				if err := filepath.WalkDir(base.String(), func(path string, d fs.DirEntry, err error) error {
-					if err != nil {
-						t.Error(err)
-						return nil
-					}
-					if !d.IsDir() {
-						return nil
-					}
-					return os.Chmod(path, 0700)
-				}); err != nil {
-					t.Fatal(err)
-				}
-			})
-
-			if c, err := pkg.New(base); err != nil {
-				t.Fatalf("New: error = %v", err)
-			} else {
-				if tc.early != nil {
-					tc.early(t, base)
-				}
-				tc.f(t, base, c)
-				tc.check(t, base)
-			}
-		})
+		}, pkg.MustDecode("ZNSQH-mjhtIbFvi51lQ0UjatjoS8_5ILrBPNWlO2LWTq9P6MJEnekYzP0esUJnVr")},
 	}
+	checkWithCache(t, testCases)
 }
 
 func TestErrors(t *testing.T) {