Moved CaptureOutput to "test" package for reuse

cmd/kn/main_test.go

@@ -24,7 +24,7 @@ import (
 	"github.com/spf13/cobra"
 	"gotest.tools/assert"
 
-	"knative.dev/client/pkg/kn/commands"
+	"knative.dev/client/lib/test"
 	"knative.dev/client/pkg/kn/root"
 	"knative.dev/client/pkg/util"
 )
@@ -243,7 +243,7 @@ func TestRunWithError(t *testing.T) {
 		},
 	}
 	for _, d := range data {
-		capture := commands.CaptureOutput(t)
+		capture := test.CaptureOutput(t)
 		printError(errors.New(d.given))
 		stdOut, errOut := capture.Close()
 
@@ -261,7 +261,7 @@ func TestRun(t *testing.T) {
 		os.Args = oldArgs
 	})()
 
-	capture := commands.CaptureOutput(t)
+	capture := test.CaptureOutput(t)
 	err := run(os.Args[1:])
 	out, _ := capture.Close()
 

lib/test/capture_output.go

@@ -0,0 +1,77 @@
+// Copyright 2020 The Knative 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.
+
+// OutputCapture allows to capture any text written to standard out or standard error
+// which is especially useful during testing.
+//
+// Call it like:
+//
+// capture := CaptureOutput(t)
+// doSomeActionThatWritesToStdOutAndStdErr()
+// stdOut, stdErr := capture.Close()
+//
+// CaptureOutpu() and capture.Close() should always come in pairs as Close() also
+// restores the old streams
+package test
+
+import (
+	"io/ioutil"
+	"os"
+	"testing"
+
+	"gotest.tools/assert"
+)
+
+type OutputCapture struct {
+	outRead, outWrite     *os.File
+	errorRead, errorWrite *os.File
+	t                     *testing.T
+
+	oldStdout *os.File
+	oldStderr *os.File
+}
+
+// CaptureOutput sets up standard our and standard error to capture any
+// output which
+func CaptureOutput(t *testing.T) OutputCapture {
+	ret := OutputCapture{
+		oldStdout: os.Stdout,
+		oldStderr: os.Stderr,
+		t:         t,
+	}
+	var err error
+	ret.outRead, ret.outWrite, err = os.Pipe()
+	assert.NilError(t, err)
+	os.Stdout = ret.outWrite
+	ret.errorRead, ret.errorWrite, err = os.Pipe()
+	assert.NilError(t, err)
+	os.Stderr = ret.errorWrite
+	return ret
+}
+
+// Close return the output collected and restores the original standard out and error streams
+// (i.e. those that were present before the call to CaptureOutput).
+func (c OutputCapture) Close() (string, string) {
+	err := c.outWrite.Close()
+	assert.NilError(c.t, err)
+	err = c.errorWrite.Close()
+	assert.NilError(c.t, err)
+	outOutput, err := ioutil.ReadAll(c.outRead)
+	assert.NilError(c.t, err)
+	errOutput, err := ioutil.ReadAll(c.errorRead)
+	assert.NilError(c.t, err)
+	os.Stdout = c.oldStdout
+	os.Stderr = c.oldStderr
+	return string(outOutput), string(errOutput)
+}

pkg/kn/commands/completion/completion_test.go

@@ -17,6 +17,7 @@ package completion
 import (
 	"testing"
 
+	"knative.dev/client/lib/test"
 	"knative.dev/client/pkg/kn/commands"
 	"knative.dev/client/pkg/util"
 
@@ -35,7 +36,7 @@ func TestCompletionUsage(t *testing.T) {
 func TestCompletionGeneration(t *testing.T) {
 	for _, shell := range []string{"bash", "zsh"} {
 		completionCmd := NewCompletionCommand(&commands.KnParams{})
-		c := commands.CaptureOutput(t)
+		c := test.CaptureOutput(t)
 		err := completionCmd.RunE(&cobra.Command{}, []string{shell})
 		assert.NilError(t, err)
 		stdOut, stdErr := c.Close()

pkg/kn/commands/testing_helper.go

@@ -16,12 +16,9 @@ package commands
 
 import (
 	"bytes"
-	"io/ioutil"
 	"os"
-	"testing"
 
 	"github.com/spf13/cobra"
-	"gotest.tools/assert"
 	"k8s.io/apimachinery/pkg/runtime"
 	clienttesting "k8s.io/client-go/testing"
 	servingv1fake "knative.dev/serving/pkg/client/clientset/versioned/typed/serving/v1/fake"
@@ -93,46 +90,6 @@ func CreateDynamicTestKnCommand(cmd *cobra.Command, knParams *KnParams, objects
 
 }
 
-type OutputCapture struct {
-	outRead, outWrite     *os.File
-	errorRead, errorWrite *os.File
-	t                     *testing.T
-
-	oldStdout *os.File
-	oldStderr *os.File
-}
-
-func CaptureOutput(t *testing.T) OutputCapture {
-	ret := OutputCapture{
-		oldStdout: os.Stdout,
-		oldStderr: os.Stderr,
-		t:         t,
-	}
-	var err error
-	ret.outRead, ret.outWrite, err = os.Pipe()
-	assert.NilError(t, err)
-	os.Stdout = ret.outWrite
-	ret.errorRead, ret.errorWrite, err = os.Pipe()
-	assert.NilError(t, err)
-	os.Stderr = ret.errorWrite
-	return ret
-}
-
-// CaptureOutput collects the current content of os.Stdout
-func (c OutputCapture) Close() (string, string) {
-	err := c.outWrite.Close()
-	assert.NilError(c.t, err)
-	err = c.errorWrite.Close()
-	assert.NilError(c.t, err)
-	outOutput, err := ioutil.ReadAll(c.outRead)
-	assert.NilError(c.t, err)
-	errOutput, err := ioutil.ReadAll(c.errorRead)
-	assert.NilError(c.t, err)
-	os.Stdout = c.oldStdout
-	os.Stderr = c.oldStderr
-	return string(outOutput), string(errOutput)
-}
-
 // NewTestCommand can be used by tes
 func NewTestCommand(subCommand *cobra.Command, params *KnParams) *cobra.Command {
 	rootCmd := &cobra.Command{

pkg/kn/commands/testing_helper_test.go

@@ -20,6 +20,8 @@ import (
 
 	"github.com/spf13/cobra"
 	"gotest.tools/assert"
+
+	"knative.dev/client/lib/test"
 )
 
 func TestCreateTestKnCommand(t *testing.T) {
@@ -56,7 +58,7 @@ func TestCreateDynamicTestKnCommand(t *testing.T) {
 }
 
 func TestCaptureStdout(t *testing.T) {
-	c := CaptureOutput(t)
+	c := test.CaptureOutput(t)
 	fmt.Print("Hello World !")
 	stdOut, stdErr := c.Close()
 	assert.Equal(t, stdErr, "")

pkg/templates/command_groups_test.go

@@ -21,7 +21,7 @@ import (
 	"github.com/spf13/cobra"
 	"gotest.tools/assert"
 
-	"knative.dev/client/pkg/kn/commands"
+	"knative.dev/client/lib/test"
 	"knative.dev/client/pkg/util"
 )
 
@@ -54,14 +54,14 @@ func TestSetUsage(t *testing.T) {
 		assert.Assert(t, cmd.DisableFlagsInUseLine)
 	}
 
-	capture := commands.CaptureOutput(t)
+	capture := test.CaptureOutput(t)
 	err := (rootCmd.UsageFunc())(rootCmd)
 	assert.NilError(t, err)
 	stdOut, stdErr := capture.Close()
 	assert.Equal(t, stdErr, "")
 	assert.Assert(t, util.ContainsAll(stdOut, "header-1", "header-2"))
 
-	capture = commands.CaptureOutput(t)
+	capture = test.CaptureOutput(t)
 	(rootCmd.HelpFunc())(rootCmd, nil)
 	stdOut, stdErr = capture.Close()
 	assert.Equal(t, stdErr, "")

pkg/templates/template_engine_test.go

@@ -23,7 +23,7 @@ import (
 	"github.com/spf13/cobra"
 	"gotest.tools/assert"
 
-	"knative.dev/client/pkg/kn/commands"
+	"knative.dev/client/lib/test"
 	"knative.dev/client/pkg/util"
 )
 
@@ -60,7 +60,7 @@ func TestUsageFunc(t *testing.T) {
 		},
 	}
 	for _, d := range data {
-		capture := commands.CaptureOutput(t)
+		capture := test.CaptureOutput(t)
 		err := (engine.usageFunc())(d.cmd)
 		assert.NilError(t, err)
 		stdOut, stdErr := capture.Close()
@@ -91,7 +91,7 @@ func TestHelpFunc(t *testing.T) {
 		},
 	}
 	for _, d := range data {
-		capture := commands.CaptureOutput(t)
+		capture := test.CaptureOutput(t)
 		(engine.helpFunc())(d.cmd, []string{})
 		stdOut, stdErr := capture.Close()
 
@@ -103,7 +103,7 @@ func TestHelpFunc(t *testing.T) {
 func TestOptionsFunc(t *testing.T) {
 	rootCmd, _ := newTemplateEngine()
 	subCmd := rootCmd.Commands()[0]
-	capture := commands.CaptureOutput(t)
+	capture := test.CaptureOutput(t)
 	err := NewGlobalOptionsFunc()(subCmd)
 	assert.NilError(t, err)
 	stdOut, stdErr := capture.Close()