internal/pipewire: add type constants

This change also centralises encoding testing.

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

internal/pipewire/pod_test.go

@@ -0,0 +1,55 @@
+package pipewire_test
+
+import (
+	"encoding"
+	"reflect"
+	"testing"
+)
+
+type encodingTestCases[V any, S interface {
+	encoding.BinaryMarshaler
+	encoding.BinaryUnmarshaler
+	*V
+}] []struct {
+	// Uninterpreted name of subtest.
+	name string
+	// Encoded data.
+	wantData []byte
+	// Value corresponding to wantData.
+	value V
+	// Expected decoding error. Skips encoding check if non-nil.
+	wantErr error
+}
+
+// run runs all test cases as subtests of [testing.T].
+func (testCases encodingTestCases[V, S]) run(t *testing.T) {
+	t.Helper()
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			t.Run("decode", func(t *testing.T) {
+				t.Parallel()
+
+				var value V
+				if err := S(&value).UnmarshalBinary(tc.wantData); err != nil {
+					t.Fatalf("UnmarshalBinary: error = %v", err)
+				}
+				if !reflect.DeepEqual(&value, &tc.value) {
+					t.Fatalf("UnmarshalBinary: %#v, want %#v", value, tc.value)
+				}
+			})
+
+			t.Run("encode", func(t *testing.T) {
+				t.Parallel()
+
+				if gotData, err := S(&tc.value).MarshalBinary(); err != nil {
+					t.Fatalf("MarshalBinary: error = %v", err)
+				} else if string(gotData) != string(tc.wantData) {
+					t.Fatalf("MarshalBinary: %#v, want %#v", gotData, tc.wantData)
+				}
+			})
+		})
+	}
+}