tests: introduce e2e suite (#422)

* mock: implement GetStatsSummary

Signed-off-by: Paulo Pires <pjpires@gmail.com>

* make: use skaffold to deploy vk

Signed-off-by: Paulo Pires <pjpires@gmail.com>

* test: add an e2e test suite

Signed-off-by: Paulo Pires <pjpires@gmail.com>

* test: add vendored code

Signed-off-by: Paulo Pires <pjpires@gmail.com>

* docs: update README.md

Signed-off-by: Paulo Pires <pjpires@gmail.com>

* ci: run e2e on circleci

Signed-off-by: Paulo Pires <pjpires@gmail.com>

* make: improve the skaffold target

Signed-off-by: Paulo Pires <pjpires@gmail.com>

* e2e: fix defer pod deletion

Signed-off-by: Paulo Pires <pjpires@gmail.com>

* e2e: improve instructions

Signed-off-by: Paulo Pires <pjpires@gmail.com>

* makefile: default shell is bash

Signed-off-by: Paulo Pires <pjpires@gmail.com>

test/e2e/framework/stats.go

@@ -0,0 +1,31 @@
+package framework
+
+import (
+	"encoding/json"
+	"strconv"
+
+	"k8s.io/apimachinery/pkg/util/net"
+	stats "k8s.io/kubernetes/pkg/kubelet/apis/stats/v1alpha1"
+)
+
+// GetStatsSummary queries the /stats/summary endpoint of the virtual-kubelet and returns the Summary object obtained as a response.
+func (f *Framework) GetStatsSummary() (*stats.Summary, error) {
+	// Query the /stats/summary endpoint.
+	b, err := f.KubeClient.CoreV1().
+		RESTClient().
+		Get().
+		Namespace(f.Namespace).
+		Resource("pods").
+		SubResource("proxy").
+		Name(net.JoinSchemeNamePort("http", f.NodeName, strconv.Itoa(10255))).
+		Suffix("/stats/summary").DoRaw()
+	if err != nil {
+		return nil, err
+	}
+	// Unmarshal the response as a Summary object and return it.
+	res := &stats.Summary{}
+	if err := json.Unmarshal(b, res); err != nil {
+		return nil, err
+	}
+	return res, nil
+}