Adding unit tests to methods of file's util

pkg/util/file/BUILD

@@ -3,6 +3,7 @@ package(default_visibility = ["//visibility:public"])
 load(
     "@io_bazel_rules_go//go:def.bzl",
     "go_library",
+    "go_test",
 )
 
 go_library(
@@ -23,3 +24,14 @@ filegroup(
     srcs = [":package-srcs"],
     tags = ["automanaged"],
 )
+
+go_test(
+    name = "go_default_test",
+    srcs = ["file_test.go"],
+    importpath = "k8s.io/kubernetes/pkg/util/file",
+    library = ":go_default_library",
+    deps = [
+        "//vendor/github.com/spf13/afero:go_default_library",
+        "//vendor/github.com/stretchr/testify/assert:go_default_library",
+    ],
+)

pkg/util/file/file_test.go

@@ -0,0 +1,149 @@
+/*
+Copyright 2017 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 file
+
+import (
+	"os"
+	"path/filepath"
+	"sort"
+	"testing"
+
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/assert"
+)
+
+func RecoverEnv(wd, tmpDir string) {
+	os.Chdir(wd)
+	os.RemoveAll(tmpDir)
+}
+
+func TestFileUtils(t *testing.T) {
+	fs := &afero.Afero{Fs: afero.NewOsFs()}
+	// Create tmp dir
+	tmpDir, err := fs.TempDir(os.TempDir(), "util_file_test_")
+	if err != nil {
+		t.Fatal("Failed to test: failed to create temp dir.")
+	}
+
+	// create tmp file
+	tmpFile, err := fs.TempFile(tmpDir, "test_file_exists_")
+	if err != nil {
+		t.Fatal("Failed to test: failed to create temp file.")
+	}
+
+	// create tmp sym link
+	tmpSymlinkName := filepath.Join(tmpDir, "test_file_exists_sym_link")
+	err = os.Symlink(tmpFile.Name(), tmpSymlinkName)
+	if err != nil {
+		t.Fatal("Failed to test: failed to create sym link.")
+	}
+
+	// create tmp sub dir
+	tmpSubDir, err := fs.TempDir(tmpDir, "sub_")
+	if err != nil {
+		t.Fatal("Failed to test: failed to create temp sub dir.")
+	}
+
+	// record the current dir
+	currentDir, err := os.Getwd()
+	if err != nil {
+		t.Fatal("Failed to test: failed to get current dir.")
+	}
+
+	// change the work dir to temp dir
+	err = os.Chdir(tmpDir)
+	if err != nil {
+		t.Fatal("Failed to test: failed to change work dir.")
+	}
+
+	// recover test enviroment
+	defer RecoverEnv(currentDir, tmpDir)
+
+	t.Run("TestFileExists", func(t *testing.T) {
+		tests := []struct {
+			name          string
+			fileName      string
+			expectedError bool
+			expectedValue bool
+		}{
+			{"file_not_exists", filepath.Join(tmpDir, "file_not_exist_case"), false, false},
+			{"file_exists", tmpFile.Name(), false, true},
+		}
+
+		for _, test := range tests {
+			realValued, realError := FileExists(test.fileName)
+			if test.expectedError {
+				assert.Errorf(t, realError, "Failed to test with '%s': %s", test.fileName, test.name)
+			} else {
+				assert.EqualValuesf(t, test.expectedValue, realValued, "Failed to test with '%s': %s", test.fileName, test.name)
+			}
+		}
+	})
+
+	t.Run("TestFileOrSymlinkExists", func(t *testing.T) {
+		tests := []struct {
+			name          string
+			fileName      string
+			expectedError bool
+			expectedValue bool
+		}{
+			{"file_not_exists", filepath.Join(tmpDir, "file_not_exist_case"), false, false},
+			{"file_exists", tmpFile.Name(), false, true},
+			{"symlink_exists", tmpSymlinkName, false, true},
+		}
+
+		for _, test := range tests {
+			realValued, realError := FileOrSymlinkExists(test.fileName)
+			if test.expectedError {
+				assert.Errorf(t, realError, "Failed to test with '%s': %s", test.fileName, test.name)
+			} else {
+				assert.EqualValuesf(t, test.expectedValue, realValued, "Failed to test with '%s': %s", test.fileName, test.name)
+			}
+		}
+	})
+
+	t.Run("TestReadDirNoStat", func(t *testing.T) {
+		_, tmpFileSimpleName := filepath.Split(tmpFile.Name())
+		_, tmpSymlinkSimpleName := filepath.Split(tmpSymlinkName)
+		_, tmpSubDirSimpleName := filepath.Split(tmpSubDir)
+
+		tests := []struct {
+			name          string
+			dirName       string
+			expectedError bool
+			expectedValue []string
+		}{
+			{"dir_not_exists", filepath.Join(tmpDir, "file_not_exist_case"), true, []string{}},
+			{"dir_is_empty", "", false, []string{tmpFileSimpleName, tmpSymlinkSimpleName, tmpSubDirSimpleName}},
+			{"dir_exists", tmpDir, false, []string{tmpFileSimpleName, tmpSymlinkSimpleName, tmpSubDirSimpleName}},
+		}
+
+		for _, test := range tests {
+			realValued, realError := ReadDirNoStat(test.dirName)
+
+			// execute sort action before compare
+			sort.Strings(realValued)
+			sort.Strings(test.expectedValue)
+
+			if test.expectedError {
+				assert.Errorf(t, realError, "Failed to test with '%s': %s", test.dirName, test.name)
+			} else {
+				assert.EqualValuesf(t, test.expectedValue, realValued, "Failed to test with '%s': %s", test.dirName, test.name)
+			}
+		}
+	})
+}