Add test coverage for MaybeWantKubectlUpdateMessage

cmd/minikube/cmd/root.go

@@ -21,6 +21,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"os"
+	"runtime"
 	"strings"
 
 	"github.com/docker/machine/libmachine/log"
@@ -102,7 +103,7 @@ Please use --v=3 to show libmachine logs, and --v=7 for debug level libmachine l
 			notify.MaybePrintUpdateTextFromGithub(os.Stderr)
 		}
 		if enableKubectlDownloadMsg {
-			util.MaybePrintKubectlDownloadMsg()
+			util.MaybePrintKubectlDownloadMsg(runtime.GOOS, os.Stderr)
 		}
 	},
 }

cmd/util/util.go

@@ -49,6 +49,14 @@ type Message struct {
 	ServiceContext `json:"serviceContext"`
 }
 
+type LookPath func(filename string) (string, error)
+
+var lookPath LookPath
+
+func init() {
+	lookPath = exec.LookPath
+}
+
 func ReportError(err error, url string) error {
 	errMsg, err := FormatError(err)
 	if err != nil {
@@ -168,13 +176,10 @@ func PromptUserForAccept(r io.Reader) bool {
 	}
 }
 
-func MaybePrintKubectlDownloadMsg() {
-	if !viper.GetBool(config.WantKubectlDownloadMsg) {
-		return
-	}
+func MaybePrintKubectlDownloadMsg(goos string, out io.Writer) {
 	verb := "run"
 	installInstructions := "curl -Lo kubectl https://storage.googleapis.com/kubernetes-release/release/%s/bin/%s/%s/kubectl && chmod +x kubectl && sudo mv kubectl /usr/local/bin/"
-	if runtime.GOOS == "windows" {
+	if goos == "windows" {
 		verb = "do"
 		installInstructions = `download kubectl from:
 https://storage.googleapis.com/kubernetes-release/release/%s/bin/%s/%s/kubectl.exe
@@ -182,13 +187,13 @@ Add kubectl to your system PATH`
 	}
 
 	var err error
-	if runtime.GOOS == "windows" {
-		_, err = exec.LookPath("kubectl.exe")
+	if goos == "windows" {
+		_, err = lookPath("kubectl.exe")
 	} else {
-		_, err = exec.LookPath("kubectl")
+		_, err = lookPath("kubectl")
 	}
 	if err != nil {
-		fmt.Fprintf(os.Stderr,
+		fmt.Fprintf(out,
 			`========================================
 kubectl could not be found on your path.  kubectl is a requirement for using minikube
 To install kubectl, please %s the following:
@@ -200,6 +205,6 @@ To disable this message, run the following:
 minikube config set WantKubectlDownloadMsg false
 ========================================
 `,
-			verb, fmt.Sprintf(installInstructions, constants.DefaultKubernetesVersion, runtime.GOOS, runtime.GOARCH))
+			verb, fmt.Sprintf(installInstructions, constants.DefaultKubernetesVersion, goos, runtime.GOARCH))
 	}
 }

cmd/util/util_test.go

@@ -17,9 +17,11 @@ limitations under the License.
 package util
 
 import (
+	"bytes"
 	"fmt"
 	"net/http"
 	"net/http/httptest"
+	"strings"
 	"testing"
 
 	"k8s.io/minikube/pkg/version"
@@ -81,3 +83,62 @@ func TestUploadError(t *testing.T) {
 		t.Fatalf("UploadError should have errored from a 400 response")
 	}
 }
+
+func revertLookPath(l LookPath) {
+	lookPath = l
+}
+
+func fakeLookPathFound(string) (string, error) { return "/usr/local/bin/kubectl", nil }
+func fakeLookPathError(string) (string, error) { return "", errors.New("") }
+
+func TestKubectlDownloadMsg(t *testing.T) {
+	var tests = []struct {
+		description string
+		lp          LookPath
+		goos        string
+		matches     string
+		noOutput    bool
+	}{
+		{
+			description: "No output when binary is found windows",
+			goos:        "windows",
+			lp:          fakeLookPathFound,
+			noOutput:    true,
+		},
+		{
+			description: "No output when binary is found darwin",
+			goos:        "darwin",
+			lp:          fakeLookPathFound,
+			noOutput:    true,
+		},
+		{
+			description: "windows kubectl not found, has .exe in output",
+			goos:        "windows",
+			lp:          fakeLookPathError,
+			matches:     ".exe",
+		},
+		{
+			description: "linux kubectl not found",
+			goos:        "linux",
+			lp:          fakeLookPathError,
+			matches:     "WantKubectlDownloadMsg",
+		},
+	}
+
+	for _, test := range tests {
+		test := test
+		t.Run(test.description, func(t *testing.T) {
+			defer revertLookPath(lookPath)
+			lookPath = test.lp
+			var b bytes.Buffer
+			MaybePrintKubectlDownloadMsg(test.goos, &b)
+			actual := b.String()
+			if actual != "" && test.noOutput {
+				t.Errorf("Got output, but kubectl binary was found")
+			}
+			if !strings.Contains(actual, test.matches) {
+				t.Errorf("Output did not contain substring expected got output %s")
+			}
+		})
+	}
+}