Add unit tests for completion command

staging/src/k8s.io/kubectl/pkg/cmd/completion/completion_test.go

@@ -0,0 +1,99 @@
+/*
+Copyright 2022 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 completion
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/spf13/cobra"
+
+	"k8s.io/cli-runtime/pkg/genericclioptions"
+)
+
+func TestBashCompletions(t *testing.T) {
+	testCases := []struct {
+		name          string
+		args          []string
+		expectedError string
+	}{
+		{
+			name: "bash",
+			args: []string{"bash"},
+		},
+		{
+			name: "zsh",
+			args: []string{"zsh"},
+		},
+		{
+			name: "fish",
+			args: []string{"fish"},
+		},
+		{
+			name: "powershell",
+			args: []string{"powershell"},
+		},
+		{
+			name: "no args",
+			args: []string{},
+			expectedError: `Shell not specified.
+See 'kubectl completion -h' for help and examples`,
+		},
+		{
+			name: "too many args",
+			args: []string{"bash", "zsh"},
+			expectedError: `Too many arguments. Expected only the shell type.
+See 'kubectl completion -h' for help and examples`,
+		},
+		{
+			name: "unsupported shell",
+			args: []string{"foo"},
+			expectedError: `Unsupported shell type "foo".
+See 'kubectl completion -h' for help and examples`,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(tt *testing.T) {
+			_, _, out, _ := genericclioptions.NewTestIOStreams()
+			parentCmd := &cobra.Command{
+				Use: "kubectl",
+			}
+			cmd := NewCmdCompletion(out, defaultBoilerPlate)
+			parentCmd.AddCommand(cmd)
+			err := RunCompletion(out, defaultBoilerPlate, cmd, tc.args)
+			if tc.expectedError == "" {
+				if err != nil {
+					tt.Fatalf("Unexpected error: %v", err)
+				}
+				if out.Len() == 0 {
+					tt.Fatalf("Output was not written")
+				}
+				if !strings.Contains(out.String(), defaultBoilerPlate) {
+					tt.Fatalf("Output does not contain boilerplate:\n%s", out.String())
+				}
+			} else {
+				if err == nil {
+					tt.Fatalf("An error was expected but no error was returned")
+				}
+				if err.Error() != tc.expectedError {
+					tt.Fatalf("Unexpected error: %v\nexpected: %v\n", err, tc.expectedError)
+				}
+			}
+		})
+	}
+}