Make it possible to fake the ServerVersion in the FakeDiscovery implementation

Kubernetes-commit: 9b060faa2aaa262104a52c57d08ec67dc60949d9

discovery/fake/discovery.go

@@ -31,8 +31,11 @@ import (
 	"k8s.io/client-go/testing"
 )
 
+// FakeDiscovery implements discovery.DiscoveryInterface and sometimes calls testing.Fake.Invoke with an action,
+// but doesn't respect the return value if any. There is a way to fake static values like ServerVersion by using the Faked... fields on the struct.
 type FakeDiscovery struct {
 	*testing.Fake
+	FakedServerVersion *version.Info
 }
 
 func (c *FakeDiscovery) ServerResourcesForGroupVersion(groupVersion string) (*metav1.APIResourceList, error) {
@@ -74,8 +77,12 @@ func (c *FakeDiscovery) ServerVersion() (*version.Info, error) {
 	action := testing.ActionImpl{}
 	action.Verb = "get"
 	action.Resource = schema.GroupVersionResource{Resource: "version"}
-
 	c.Invokes(action, nil)
+
+	if c.FakedServerVersion != nil {
+		return c.FakedServerVersion, nil
+	}
+
 	versionInfo := kubeversion.Get()
 	return &versionInfo, nil
 }

discovery/fake/test/discovery_test.go

@@ -0,0 +1,46 @@
+/*
+Copyright 2017 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 fake
+
+import (
+	"testing"
+
+	"k8s.io/apimachinery/pkg/version"
+	fakediscovery "k8s.io/client-go/discovery/fake"
+	fakeclientset "k8s.io/client-go/kubernetes/fake"
+)
+
+func TestFakingServerVersion(t *testing.T) {
+	client := fakeclientset.NewSimpleClientset()
+	fakeDiscovery, ok := client.Discovery().(*fakediscovery.FakeDiscovery)
+	if !ok {
+		t.Fatalf("couldn't convert Discovery() to *FakeDiscovery")
+	}
+
+	testGitCommit := "v1.0.0"
+	fakeDiscovery.FakedServerVersion = &version.Info{
+		GitCommit: testGitCommit,
+	}
+
+	sv, err := client.Discovery().ServerVersion()
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if sv.GitCommit != testGitCommit {
+		t.Fatalf("unexpected faked discovery return value: %q", sv.GitCommit)
+	}
+}