Add some validation helpers

validation.go

@@ -18,12 +18,20 @@ type Validator interface {
 }
 
 // FieldError describes an error on a field
+// Typically .Error() has both Name() and Err() together, hence the reason
+// for separation.
 type FieldError interface {
 	error
 	Name() string
 	Err() error
 }
 
+// ErrorMap is a shortcut to change []error into ErrorList and call Map on it since
+// this is a common operation.
+func ErrorMap(e []error) map[string][]string {
+	return ErrorList(e).Map()
+}
+
 // ErrorList is simply a slice of errors with helpers.
 type ErrorList []error
 

validation_test.go

@@ -78,3 +78,15 @@ func TestErrorList_Map(t *testing.T) {
 		t.Error("Wrong unkown error at 0:", unknownErrs[0])
 	}
 }
+
+func TestErrorList_MapHelper(t *testing.T) {
+	t.Parallel()
+
+	errList := []error{
+		mockFieldError{"username", errors.New("")},
+		mockFieldError{"username", errors.New("")},
+		mockFieldError{"password", errors.New("")},
+	}
+
+	var _ map[string][]string = ErrorMap(errList)
+}