Merge pull request #46906 from zhangxiaoyu-zidif/Add-testcase-for-namespace

Automatic merge from submit-queue (batch tested with PRs 47403, 46646, 46906, 46527, 46792)

Add test case for namespace

**What this PR does / why we need it**:
Unit test case need add that when name is "".

**Special notes for your reviewer**:
refer to https://github.com/kubernetes/kubernetes/blob/master/pkg/kubectl/namespace.go#L74

**Release note**:

```release-note
NONE
```

pkg/kubectl/namespace_test.go

@@ -52,6 +52,12 @@ func TestNamespaceGenerate(t *testing.T) {
 			},
 			expectErr: true,
 		},
+		{
+			params: map[string]interface{}{
+				"name": "",
+			},
+			expectErr: true,
+		},
 		{
 			params: map[string]interface{}{
 				"name": nil,