Merge pull request #41277 from apprenda/kubeadm_join_test-cmds

Automatic merge from submit-queue (batch tested with PRs 41216, 41362, 41275, 41277, 41412)

kubeadm: test-cmd: join{config, discovery}

**What this PR does / why we need it**: Adding test-cmds for kubeadm join {config, discovery}. Will followup with more test-cmds for other flags as soon as validation for the flags works. 

Adding tests is a WIP from #34136

**Special notes for your reviewer**: /cc @luxas @pires 

**Release note**:
```release-note
NONE
```

cmd/kubeadm/test/cmd/BUILD

@@ -18,6 +18,7 @@ go_test(
     name = "go_default_test",
     srcs = [
         "init_test.go",
+        "join_test.go",
         "token_test.go",
     ],
     args = ["--kubeadm-path=../../kubeadm"],

cmd/kubeadm/test/cmd/join_test.go

@@ -0,0 +1,77 @@
+/*
+Copyright 2016 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 kubeadm
+
+import "testing"
+
+func TestCmdJoinConfig(t *testing.T) {
+	if *kubeadmCmdSkip {
+		t.Log("kubeadm cmd tests being skipped")
+		t.Skip()
+	}
+
+	var initTest = []struct {
+		args     string
+		expected bool
+	}{
+		{"--config=foobar", false},
+		{"--config=/does/not/exist/foo/bar", false},
+	}
+
+	for _, rt := range initTest {
+		_, _, actual := RunCmd(*kubeadmPath, "join", rt.args, "--skip-preflight-checks")
+		if (actual == nil) != rt.expected {
+			t.Errorf(
+				"failed CmdJoinConfig running 'kubeadm join %s' with an error: %v\n\texpected: %t\n\t  actual: %t",
+				rt.args,
+				actual,
+				rt.expected,
+				(actual == nil),
+			)
+		}
+		kubeadmReset()
+	}
+}
+
+func TestCmdJoinDiscovery(t *testing.T) {
+	if *kubeadmCmdSkip {
+		t.Log("kubeadm cmd tests being skipped")
+		t.Skip()
+	}
+
+	var initTest = []struct {
+		args     string
+		expected bool
+	}{
+		{"--discovery=foobar", false},
+		{"--dicovery=magic", false},
+	}
+
+	for _, rt := range initTest {
+		_, _, actual := RunCmd(*kubeadmPath, "join", rt.args, "--skip-preflight-checks")
+		if (actual == nil) != rt.expected {
+			t.Errorf(
+				"failed CmdJoinDiscovery running 'kubeadm join %s' with an error: %v\n\texpected: %t\n\t  actual: %t",
+				rt.args,
+				actual,
+				rt.expected,
+				(actual == nil),
+			)
+		}
+		kubeadmReset()
+	}
+}