Fix extra string actions

internal/clipboard/service_test.go

@@ -48,6 +48,30 @@ func TestServiceCopiesUsernamePasswordAndURL(t *testing.T) {
 	}
 }
 
+func TestServiceCopiesCustomField(t *testing.T) {
+	t.Parallel()
+
+	var writer memoryWriter
+	service := Service{Writer: &writer}
+	model := vault.Model{
+		Entries: []vault.Entry{
+			{
+				ID: "vault-console",
+				Fields: map[string]string{
+					"OTPSeed": "green-light",
+				},
+			},
+		},
+	}
+
+	if err := service.CopyCustomField(model, "vault-console", "OTPSeed"); err != nil {
+		t.Fatalf("CopyCustomField(vault-console, OTPSeed) error = %v", err)
+	}
+	if writer.content != "green-light" {
+		t.Fatalf("clipboard content = %q, want green-light", writer.content)
+	}
+}
+
 func TestServiceRejectsUnknownEntryAndUnsupportedTarget(t *testing.T) {
 	t.Parallel()