Merge pull request #2147 from dgageot/override-helper

Test helper to override value for tests

cmd/skaffold/app/cmd/build_test.go

@@ -68,17 +68,17 @@ func TestQuietFlag(t *testing.T) {
 
 	for _, test := range tests {
 		t.Run(test.description, func(t *testing.T) {
-			defer func(flag bool) { quietFlag = flag }(quietFlag)
-			quietFlag = true
+			restore := testutil.Override(t, &quietFlag, true)
+			defer restore()
+
+			restoreFn := testutil.Override(t, &createRunnerAndBuildFunc, test.mock)
+			defer restoreFn()
 
-			defer func(tf *flags.TemplateFlag) { buildFormatFlag = tf }(buildFormatFlag)
 			if test.template != "" {
-				buildFormatFlag = flags.NewTemplateFlag(test.template, flags.BuildOutput{})
+				restoreTemplate := testutil.Override(t, &buildFormatFlag, flags.NewTemplateFlag(test.template, flags.BuildOutput{}))
+				defer restoreTemplate()
 			}
 
-			defer func(f func(context.Context, io.Writer) ([]build.Artifact, error)) { createRunnerAndBuildFunc = f }(createRunnerAndBuildFunc)
-			createRunnerAndBuildFunc = test.mock
-
 			var output bytes.Buffer
 			err := doBuild(&output)
 
@@ -116,8 +116,8 @@ func TestRunBuild(t *testing.T) {
 	}
 	for _, test := range tests {
 		t.Run(test.description, func(t *testing.T) {
-			defer func(f func(context.Context, io.Writer) ([]build.Artifact, error)) { createRunnerAndBuildFunc = f }(createRunnerAndBuildFunc)
-			createRunnerAndBuildFunc = test.mock
+			restore := testutil.Override(t, &createRunnerAndBuildFunc, test.mock)
+			defer restore()
 
 			err := doBuild(ioutil.Discard)
 

cmd/skaffold/app/skaffold_test.go

@@ -31,8 +31,8 @@ func TestMainHelp(t *testing.T) {
 		errOutput bytes.Buffer
 	)
 
-	defer func(args []string) { os.Args = args }(os.Args)
-	os.Args = []string{"skaffold", "help"}
+	restore := testutil.Override(t, &os.Args, []string{"skaffold", "help"})
+	defer restore()
 
 	err := Run(&output, &errOutput)
 
@@ -42,8 +42,8 @@ func TestMainHelp(t *testing.T) {
 }
 
 func TestMainUnknownCommand(t *testing.T) {
-	defer func(args []string) { os.Args = args }(os.Args)
-	os.Args = []string{"skaffold", "unknown"}
+	restore := testutil.Override(t, &os.Args, []string{"skaffold", "unknown"})
+	defer restore()
 
 	err := Run(ioutil.Discard, ioutil.Discard)
 

testutil/util.go

@@ -19,6 +19,7 @@ package testutil
 import (
 	"errors"
 	"fmt"
+	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
 	"os"
@@ -155,3 +156,50 @@ func ServeFile(t *testing.T, content []byte) (url string, tearDown func()) {
 
 	return ts.URL, ts.Close
 }
+
+// CreateTempFileWithContents creates a temporary file in the dir specified or
+// os.TempDir by default with contents mentioned.
+func CreateTempFileWithContents(t *testing.T, dir string, name string, content []byte) string {
+	t.Helper()
+	tmpfile, err := ioutil.TempFile(dir, name)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := tmpfile.Write(content); err != nil {
+		t.Fatal(err)
+	}
+	if err := tmpfile.Close(); err != nil {
+		t.Fatal(err)
+	}
+	return tmpfile.Name()
+}
+
+// Override sets a dest variable to a given value.
+// Returns the function to call to restore the variable
+// to its original state.
+func Override(t *testing.T, dest, tmp interface{}) func() {
+	t.Helper()
+
+	defer func() {
+		if r := recover(); r != nil {
+			t.Error("temporary value is of invalid type")
+		}
+	}()
+
+	dValue := reflect.ValueOf(dest).Elem()
+
+	// Save current value
+	curValue := reflect.New(dValue.Type()).Elem()
+	curValue.Set(dValue)
+
+	// Set to temporary value
+	var tmpV reflect.Value
+	if tmp == nil {
+		tmpV = reflect.Zero(dValue.Type())
+	} else {
+		tmpV = reflect.ValueOf(tmp)
+	}
+	dValue.Set(tmpV)
+
+	return func() { dValue.Set(curValue) }
+}

testutil/util_test.go

@@ -0,0 +1,48 @@
+/*
+Copyright 2019 The Skaffold 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 testutil
+
+import "testing"
+
+var (
+	strVariable = "original"
+	fnVariable  = func() string { return "original" }
+)
+
+func TestOverride(t *testing.T) {
+	restore := Override(t, &strVariable, "temporary")
+	CheckDeepEqual(t, "temporary", strVariable)
+
+	restore()
+	CheckDeepEqual(t, "original", strVariable)
+}
+
+func TestOverrideFunction(t *testing.T) {
+	restore := Override(t, &fnVariable, func() string { return "temporary" })
+	CheckDeepEqual(t, "temporary", fnVariable())
+
+	restore()
+	CheckDeepEqual(t, "original", fnVariable())
+}
+
+func TestOverrideToNil(t *testing.T) {
+	restore := Override(t, &fnVariable, nil)
+	CheckDeepEqual(t, true, fnVariable == nil)
+
+	restore()
+	CheckDeepEqual(t, "original", fnVariable())
+}