Make Reflector helpers reusable.

Scheduler uses Reflector from pkg/client/cache.
It defines some helper classes.
I'd like to use those helpers with pkg/client/cache
in kube-proxy and kubelet too.

pkg/client/cache/listwatch.go

@@ -0,0 +1,52 @@
+/*
+Copyright 2015 Google Inc. All rights reserved.
+
+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 cache
+
+import (
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/client"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/labels"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/runtime"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/watch"
+)
+
+// ListWatch knows how to list and watch a set of apiserver resources.  It satisfies the ListerWatcher interface.
+// It is a convenience function for users of NewReflector, etc.
+type ListWatch struct {
+	Client        *client.Client
+	FieldSelector labels.Selector
+	Resource      string
+}
+
+// ListWatch knows how to list and watch a set of apiserver resources.
+func (lw *ListWatch) List() (runtime.Object, error) {
+	return lw.Client.
+		Get().
+		Resource(lw.Resource).
+		SelectorParam("fields", lw.FieldSelector).
+		Do().
+		Get()
+}
+
+func (lw *ListWatch) Watch(resourceVersion string) (watch.Interface, error) {
+	return lw.Client.
+		Get().
+		Prefix("watch").
+		Resource(lw.Resource).
+		SelectorParam("fields", lw.FieldSelector).
+		Param("resourceVersion", resourceVersion).
+		Watch()
+}

pkg/client/cache/listwatch_test.go

@@ -0,0 +1,123 @@
+/*
+Copyright 2015 Google Inc. All rights reserved.
+
+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 cache
+
+import (
+	"net/http/httptest"
+	"testing"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/testapi"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/client"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/labels"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
+)
+
+func parseSelectorOrDie(s string) labels.Selector {
+	selector, err := labels.ParseSelector(s)
+	if err != nil {
+		panic(err)
+	}
+	return selector
+}
+
+func TestListWatchesCanList(t *testing.T) {
+	table := []struct {
+		location string
+		lw       ListWatch
+	}{
+		// Minion
+		{
+			location: "/api/" + testapi.Version() + "/minions",
+			lw: ListWatch{
+				FieldSelector: parseSelectorOrDie(""),
+				Resource:      "minions",
+			},
+		},
+		// pod with "assigned" field selector.
+		{
+			location: "/api/" + testapi.Version() + "/pods?fields=DesiredState.Host%3D",
+			lw: ListWatch{
+				FieldSelector: labels.Set{"DesiredState.Host": ""}.AsSelector(),
+				Resource:      "pods",
+			},
+		},
+	}
+
+	for _, item := range table {
+		handler := util.FakeHandler{
+			StatusCode:   500,
+			ResponseBody: "",
+			T:            t,
+		}
+		server := httptest.NewServer(&handler)
+		defer server.Close()
+		item.lw.Client = client.NewOrDie(&client.Config{Host: server.URL, Version: testapi.Version()})
+		// This test merely tests that the correct request is made.
+		item.lw.List()
+		handler.ValidateRequest(t, item.location, "GET", nil)
+	}
+}
+
+func TestListWatchesCanWatch(t *testing.T) {
+	table := []struct {
+		rv       string
+		location string
+		lw       ListWatch
+	}{
+		// Minion
+		{
+			location: "/api/" + testapi.Version() + "/watch/minions?resourceVersion=",
+			rv:       "",
+			lw: ListWatch{
+				FieldSelector: parseSelectorOrDie(""),
+				Resource:      "minions",
+			},
+		},
+		{
+			location: "/api/" + testapi.Version() + "/watch/minions?resourceVersion=42",
+			rv:       "42",
+			lw: ListWatch{
+				FieldSelector: parseSelectorOrDie(""),
+				Resource:      "minions",
+			},
+		},
+		// pod with "assigned" field selector.
+		{
+			location: "/api/" + testapi.Version() + "/watch/pods?fields=DesiredState.Host%3D&resourceVersion=0",
+			rv:       "0",
+			lw: ListWatch{
+				FieldSelector: labels.Set{"DesiredState.Host": ""}.AsSelector(),
+				Resource:      "pods",
+			},
+		},
+	}
+
+	for _, item := range table {
+		handler := util.FakeHandler{
+			StatusCode:   500,
+			ResponseBody: "",
+			T:            t,
+		}
+		server := httptest.NewServer(&handler)
+		defer server.Close()
+		item.lw.Client = client.NewOrDie(&client.Config{Host: server.URL, Version: testapi.Version()})
+
+		// This test merely tests that the correct request is made.
+		item.lw.Watch(item.rv)
+		handler.ValidateRequest(t, item.location, "GET", nil)
+	}
+}