Implement kind visitor library for kubectl

- Will be used to replace "Kind" switch statements
- Allow for removal of go library dependency on kubernetes/kubernetes unversioned api packages
- Better support for ensuring all types are accounted for

pkg/kubectl/BUILD

@@ -184,6 +184,7 @@ filegroup(
     name = "all-srcs",
     srcs = [
         ":package-srcs",
+        "//pkg/kubectl/apps:all-srcs",
         "//pkg/kubectl/cmd:all-srcs",
         "//pkg/kubectl/metricsutil:all-srcs",
         "//pkg/kubectl/plugins:all-srcs",

pkg/kubectl/apps/BUILD

@@ -0,0 +1,42 @@
+package(default_visibility = ["//visibility:public"])
+
+licenses(["notice"])
+
+load(
+    "@io_bazel_rules_go//go:def.bzl",
+    "go_library",
+    "go_test",
+)
+
+go_library(
+    name = "go_default_library",
+    srcs = ["kind_visitor.go"],
+    tags = ["automanaged"],
+    deps = ["//vendor/k8s.io/apimachinery/pkg/runtime/schema:go_default_library"],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [":package-srcs"],
+    tags = ["automanaged"],
+)
+
+go_test(
+    name = "go_default_xtest",
+    srcs = [
+        "apps_suite_test.go",
+        "kind_visitor_test.go",
+    ],
+    deps = [
+        ":go_default_library",
+        "//vendor/github.com/onsi/ginkgo:go_default_library",
+        "//vendor/github.com/onsi/gomega:go_default_library",
+    ],
+)

pkg/kubectl/apps/apps_suite_test.go

@@ -0,0 +1,29 @@
+/*
+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 apps_test
+
+import (
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+
+	"testing"
+)
+
+func TestApps(t *testing.T) {
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "Apps Suite")
+}

pkg/kubectl/apps/kind_visitor.go

@@ -0,0 +1,95 @@
+/*
+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 apps
+
+import (
+	"fmt"
+
+	"k8s.io/apimachinery/pkg/runtime/schema"
+)
+
+// KindVisitor is used with GroupKindElement to call a particular function depending on the
+// Kind of a schema.GroupKind
+type KindVisitor interface {
+	VisitDaemonSet(kind GroupKindElement)
+	VisitDeployment(kind GroupKindElement)
+	VisitJob(kind GroupKindElement)
+	VisitPod(kind GroupKindElement)
+	VisitReplicaSet(kind GroupKindElement)
+	VisitReplicationController(kind GroupKindElement)
+	VisitStatefulSet(kind GroupKindElement)
+}
+
+// GroupKindElement defines a Kubernetes API group elem
+type GroupKindElement schema.GroupKind
+
+// Accept calls the Visit method on visitor that corresponds to elem's Kind
+func (elem GroupKindElement) Accept(visitor KindVisitor) error {
+	if elem.GroupMatch("apps", "extensions") && elem.Kind == "DaemonSet" {
+		visitor.VisitDaemonSet(elem)
+		return nil
+	}
+	if elem.GroupMatch("apps", "extensions") && elem.Kind == "Deployment" {
+		visitor.VisitDeployment(elem)
+		return nil
+	}
+	if elem.GroupMatch("apps", "extensions") && elem.Kind == "Job" {
+		visitor.VisitDeployment(elem)
+		return nil
+	}
+	if elem.GroupMatch("", "core") && elem.Kind == "Pod" {
+		visitor.VisitPod(elem)
+		return nil
+	}
+	if elem.GroupMatch("apps", "extensions") && elem.Kind == "ReplicaSet" {
+		visitor.VisitReplicationController(elem)
+		return nil
+	}
+	if elem.GroupMatch("", "core") && elem.Kind == "ReplicationController" {
+		visitor.VisitReplicationController(elem)
+		return nil
+	}
+	if elem.GroupMatch("apps") && elem.Kind == "StatefulSet" {
+		visitor.VisitStatefulSet(elem)
+		return nil
+	}
+	return fmt.Errorf("no visitor method exists for %v", elem)
+}
+
+// GroupMatch returns true if and only if elem's group matches one
+// of the group arguments
+func (elem GroupKindElement) GroupMatch(groups ...string) bool {
+	for _, g := range groups {
+		if elem.Group == g {
+			return true
+		}
+	}
+	return false
+}
+
+// DefaultKindVisitor implements KindVisitor with no-op functions.
+type DefaultKindVisitor struct{}
+
+var _ KindVisitor = &DefaultKindVisitor{}
+
+func (*DefaultKindVisitor) VisitDaemonSet(kind GroupKindElement)             {}
+func (*DefaultKindVisitor) VisitDeployment(kind GroupKindElement)            {}
+func (*DefaultKindVisitor) VisitJob(kind GroupKindElement)                   {}
+func (*DefaultKindVisitor) VisitPod(kind GroupKindElement)                   {}
+func (*DefaultKindVisitor) VisitReplicaSet(kind GroupKindElement)            {}
+func (*DefaultKindVisitor) VisitReplicationController(kind GroupKindElement) {}
+func (*DefaultKindVisitor) VisitStatefulSet(kind GroupKindElement)           {}

pkg/kubectl/apps/kind_visitor_test.go

@@ -0,0 +1,190 @@
+/*
+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 apps_test
+
+import (
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+
+	"k8s.io/kubernetes/pkg/kubectl/apps"
+)
+
+var _ = Describe("When KindVisitor accepts a GroupKind", func() {
+
+	var visitor *TestKindVisitor
+
+	BeforeEach(func() {
+		visitor = &TestKindVisitor{map[string]int{}}
+	})
+
+	It("should Visit DaemonSet iff the Kind is a DaemonSet", func() {
+		kind := apps.GroupKindElement{
+			Kind:  "DaemonSet",
+			Group: "apps",
+		}
+		Expect(kind.Accept(visitor)).ShouldNot(HaveOccurred())
+		Expect(visitor.visits).To(Equal(map[string]int{
+			"DaemonSet": 1,
+		}))
+
+		kind = apps.GroupKindElement{
+			Kind:  "DaemonSet",
+			Group: "extensions",
+		}
+		Expect(kind.Accept(visitor)).ShouldNot(HaveOccurred())
+		Expect(visitor.visits).To(Equal(map[string]int{
+			"DaemonSet": 2,
+		}))
+	})
+
+	It("should Visit Deployment iff the Kind is a Deployment", func() {
+		kind := apps.GroupKindElement{
+			Kind:  "Deployment",
+			Group: "apps",
+		}
+		Expect(kind.Accept(visitor)).ShouldNot(HaveOccurred())
+		Expect(visitor.visits).To(Equal(map[string]int{
+			"Deployment": 1,
+		}))
+
+		kind = apps.GroupKindElement{
+			Kind:  "Deployment",
+			Group: "extensions",
+		}
+		Expect(kind.Accept(visitor)).ShouldNot(HaveOccurred())
+		Expect(visitor.visits).To(Equal(map[string]int{
+			"Deployment": 2,
+		}))
+	})
+
+	It("should Visit Job iff the Kind is a Job", func() {
+		kind := apps.GroupKindElement{
+			Kind:  "Job",
+			Group: "apps",
+		}
+		Expect(kind.Accept(visitor)).ShouldNot(HaveOccurred())
+		Expect(visitor.visits).To(Equal(map[string]int{
+			"Job": 1,
+		}))
+
+		kind = apps.GroupKindElement{
+			Kind:  "Job",
+			Group: "extensions",
+		}
+		Expect(kind.Accept(visitor)).ShouldNot(HaveOccurred())
+		Expect(visitor.visits).To(Equal(map[string]int{
+			"Job": 2,
+		}))
+	})
+
+	It("should Visit Pod iff the Kind is a Pod", func() {
+		kind := apps.GroupKindElement{
+			Kind:  "Pod",
+			Group: "",
+		}
+		Expect(kind.Accept(visitor)).ShouldNot(HaveOccurred())
+		Expect(visitor.visits).To(Equal(map[string]int{
+			"Pod": 1,
+		}))
+
+		kind = apps.GroupKindElement{
+			Kind:  "Pod",
+			Group: "core",
+		}
+		Expect(kind.Accept(visitor)).ShouldNot(HaveOccurred())
+		Expect(visitor.visits).To(Equal(map[string]int{
+			"Pod": 2,
+		}))
+	})
+
+	It("should Visit ReplicationController iff the Kind is a ReplicationController", func() {
+		kind := apps.GroupKindElement{
+			Kind:  "ReplicationController",
+			Group: "",
+		}
+		Expect(kind.Accept(visitor)).ShouldNot(HaveOccurred())
+		Expect(visitor.visits).To(Equal(map[string]int{
+			"ReplicationController": 1,
+		}))
+
+		kind = apps.GroupKindElement{
+			Kind:  "ReplicationController",
+			Group: "core",
+		}
+		Expect(kind.Accept(visitor)).ShouldNot(HaveOccurred())
+		Expect(visitor.visits).To(Equal(map[string]int{
+			"ReplicationController": 2,
+		}))
+	})
+
+	It("should Visit ReplicaSet iff the Kind is a ReplicaSet", func() {
+		kind := apps.GroupKindElement{
+			Kind:  "ReplicaSet",
+			Group: "apps",
+		}
+		Expect(kind.Accept(visitor)).ShouldNot(HaveOccurred())
+		Expect(visitor.visits).To(Equal(map[string]int{
+			"ReplicaSet": 1,
+		}))
+
+		kind = apps.GroupKindElement{
+			Kind:  "ReplicaSet",
+			Group: "extensions",
+		}
+		Expect(kind.Accept(visitor)).ShouldNot(HaveOccurred())
+		Expect(visitor.visits).To(Equal(map[string]int{
+			"ReplicaSet": 2,
+		}))
+	})
+
+	It("should Visit StatefulSet iff the Kind is a StatefulSet", func() {
+		kind := apps.GroupKindElement{
+			Kind:  "StatefulSet",
+			Group: "apps",
+		}
+		Expect(kind.Accept(visitor)).ShouldNot(HaveOccurred())
+		Expect(visitor.visits).To(Equal(map[string]int{
+			"StatefulSet": 1,
+		}))
+	})
+
+	It("should give an error if the Kind is unknown", func() {
+		kind := apps.GroupKindElement{
+			Kind:  "Unknown",
+			Group: "apps",
+		}
+		Expect(kind.Accept(visitor)).Should(HaveOccurred())
+		Expect(visitor.visits).To(Equal(map[string]int{}))
+	})
+})
+
+// TestKindVisitor increments a value each time a Visit method was called
+type TestKindVisitor struct {
+	visits map[string]int
+}
+
+var _ apps.KindVisitor = &TestKindVisitor{}
+
+func (t *TestKindVisitor) Visit(kind apps.GroupKindElement) { t.visits[kind.Kind] += 1 }
+
+func (t *TestKindVisitor) VisitDaemonSet(kind apps.GroupKindElement)             { t.Visit(kind) }
+func (t *TestKindVisitor) VisitDeployment(kind apps.GroupKindElement)            { t.Visit(kind) }
+func (t *TestKindVisitor) VisitJob(kind apps.GroupKindElement)                   { t.Visit(kind) }
+func (t *TestKindVisitor) VisitPod(kind apps.GroupKindElement)                   { t.Visit(kind) }
+func (t *TestKindVisitor) VisitReplicaSet(kind apps.GroupKindElement)            { t.Visit(kind) }
+func (t *TestKindVisitor) VisitReplicationController(kind apps.GroupKindElement) { t.Visit(kind) }
+func (t *TestKindVisitor) VisitStatefulSet(kind apps.GroupKindElement)           { t.Visit(kind) }