Allow ValidationErrorList to be filtered

Expose basic filters on an error list to ignore certain error types.
This can be used by client code to ignore errors on common schema
types like "metadata.name" or the NotFound error type.

pkg/api/errors/validation_test.go

@@ -93,6 +93,32 @@ func TestValidationErrorUsefulMessage(t *testing.T) {
 	}
 }
 
+func TestErrListFilter(t *testing.T) {
+	list := ValidationErrorList{
+		NewFieldInvalid("test.field", "", ""),
+		NewFieldInvalid("field.test", "", ""),
+		NewFieldDuplicate("test", "value"),
+	}
+	if len(list.Filter(NewValidationErrorTypeMatcher(ValidationErrorTypeDuplicate))) != 2 {
+		t.Errorf("should not filter")
+	}
+	if len(list.Filter(NewValidationErrorTypeMatcher(ValidationErrorTypeInvalid))) != 1 {
+		t.Errorf("should filter")
+	}
+	if len(list.Filter(NewValidationErrorFieldPrefixMatcher("test"))) != 1 {
+		t.Errorf("should filter")
+	}
+	if len(list.Filter(NewValidationErrorFieldPrefixMatcher("test."))) != 2 {
+		t.Errorf("should filter")
+	}
+	if len(list.Filter(NewValidationErrorFieldPrefixMatcher(""))) != 0 {
+		t.Errorf("should filter")
+	}
+	if len(list.Filter(NewValidationErrorFieldPrefixMatcher("field."), NewValidationErrorTypeMatcher(ValidationErrorTypeDuplicate))) != 1 {
+		t.Errorf("should filter")
+	}
+}
+
 func TestErrListPrefix(t *testing.T) {
 	testCases := []struct {
 		Err      *ValidationError