Stub Google::Auth.get_application_default in tests so that they pass …

…on systems without credentials.

test/test_kubeclient.rb

@@ -625,47 +625,47 @@ def test_auth_use_default_gcp_success
     stub_request(:get, %r{/api/v1$})
       .to_return(body: open_test_file('core_api_resource_list.json'),
                  status: 200)
-    stub_request(:post, 'https://www.googleapis.com/oauth2/v3/token')
-      .to_return(status: 200,
-                 body: '{
-                         "access_token": "valid_token",
-                         "token_type": "Bearer",
-                         "expires_in": 3600,
-                         "id_token": "1234567890"
-                        }',
-                 headers: { 'Content-Type' => 'application/json; charset=UTF-8' })
     stub_request(:get, 'http://localhost:8080/api/v1/pods')
       .with(headers: { Authorization: 'Bearer valid_token' })
       .to_return(body: open_test_file('pod_list.json'),
                  status: 200)
 
-    client = Kubeclient::Client.new('http://localhost:8080/api/',
-                                    auth_options: {
-                                      use_default_gcp: true
-                                    })
-
-    pods = client.get_pods
+    auth = Minitest::Mock.new
+    auth.expect(:apply, nil, [{}])
+    auth.expect(:access_token, 'valid_token')
+    Google::Auth.stub(:get_application_default, auth) do
+      client = Kubeclient::Client.new('http://localhost:8080/api/',
+                                      auth_options: {
+                                        use_default_gcp: true
+                                      })
+      pods = client.get_pods
 
-    assert_equal('Pod', pods.kind)
-    assert_equal(1, pods.size)
+      assert_equal('Pod', pods.kind)
+      assert_equal(1, pods.size)
+    end
   end
 
   def test_auth_use_default_gcp_failure
     stub_request(:get, %r{/api/v1$})
       .to_return(body: open_test_file('core_api_resource_list.json'),
                  status: 200)
-    stub_request(:post, 'https://www.googleapis.com/oauth2/v3/token')
-      .to_return(status: 401,
-                 body: '',
-                 headers: { 'Content-Type' => 'application/json; charset=UTF-8' })
 
     expected_msg = 'Authorization failed.'
+    response = OpenStruct.new(body: '', status: 401)
+    auth = Minitest::Mock.new
+    auth.expect(:apply, nil) do
+      fail Signet::AuthorizationError.new(expected_msg, response: response)
+    end
+
     exception = assert_raises(KubeException) do
-      Kubeclient::Client.new('http://localhost:8080',
-                             auth_options: {
-                               use_default_gcp: true
-                             })
+      Google::Auth.stub(:get_application_default, auth) do
+        Kubeclient::Client.new('http://localhost:8080',
+                               auth_options: {
+                                 use_default_gcp: true
+                               })
+      end
     end
+
     assert_equal(401, exception.error_code)
     assert_equal(expected_msg, exception.message)
   end