Enhancement for format error message

- add yaml format error handler
- silent usage when build command fails

pkg/internal/error/yamlformaterror_test.go

@@ -0,0 +1,67 @@
+/*
+Copyright 2018 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package error
+
+import (
+	"bytes"
+	"fmt"
+	"testing"
+
+	"github.com/kubernetes-sigs/kustomize/pkg/constants"
+	yaml "k8s.io/apimachinery/pkg/util/yaml"
+)
+
+var (
+	filepath = "/path/to/" + constants.KustomizationFileName
+	expected = "YAML file [/path/to/kustomization.yaml] encounters a format error.\n" +
+		"error converting YAML to JSON: yaml: line 2: found character that cannot start any token\n"
+	doc = `
+	foo:
+	- fiz
+	- fu
+	`
+)
+
+func TestYamlFormatError_Error(t *testing.T) {
+	testErr := YamlFormatError{
+		Path:     filepath,
+		ErrorMsg: "error converting YAML to JSON: yaml: line 2: found character that cannot start any token",
+	}
+	if testErr.Error() != expected {
+		t.Errorf("Expected : %s\n, but found : %s\n", expected, testErr.Error())
+	}
+}
+
+func TestErrorHandler(t *testing.T) {
+	f := foo{}
+	err := yaml.NewYAMLToJSONDecoder(bytes.NewReader([]byte(doc))).Decode(&f)
+	testErr := ErrorHandler(err, filepath)
+	expectedErr := fmt.Errorf("Format error message")
+	fmtErr := ErrorHandler(expectedErr, filepath)
+	if fmtErr.Error() != expectedErr.Error() {
+		t.Errorf("Expected returning fmt.Error, but found %T", fmtErr)
+	}
+	if _, ok := testErr.(YamlFormatError); !ok {
+		t.Errorf("Expected returning YamlFormatError, but found %T", testErr)
+	}
+	if testErr == nil || testErr.Error() != expected {
+		t.Errorf("Expected : %s\n, but found : %s\n", expected, testErr.Error())
+	}
+}
+
+//type foo struct
+type foo struct{}