HEAVY: finish music service migration, tidy up services, more tests

errors/validation_test.go

@@ -0,0 +1,26 @@
+package errors_test
+
+import (
+	"arimelody-web/errors"
+	goErrors "errors"
+	"testing"
+
+	"gotest.tools/v3/assert"
+)
+
+func Test_ValidationError(t *testing.T) {
+    var err error
+    message := "invalid input"
+
+    t.Run("can create error", func(t *testing.T) {
+        err = errors.NewValidationError(message)
+        assert.Error(t, err, message)
+    })
+
+    t.Run("validator returns true for valid error", func(t *testing.T) {
+        assert.Equal(t, errors.IsValidationError(err), true)
+    })
+    t.Run("validator returns false for invalid error", func(t *testing.T) {
+        assert.Equal(t, errors.IsValidationError(goErrors.New("other error")), false)
+    })
+}