Retry fetching http urls passed to '-f' in kubectl.

Closes #24089.

pkg/kubectl/resource/visitor_test.go

@@ -0,0 +1,83 @@
+/*
+Copyright 2016 The Kubernetes Authors 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 resource
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestVisitorHttpGet(t *testing.T) {
+	instance := &URLVisitor{}
+
+	// Test retries on errors
+	i := 0
+	expectedErr := fmt.Errorf("Failed to get http")
+	actualBytes, actualErr := instance.readHttpWithRetries(func(url string) (int, string, io.ReadCloser, error) {
+		assert.Equal(t, "hello", url)
+		i++
+		if i > 2 {
+			return 0, "", nil, expectedErr
+		}
+		return 0, "", nil, fmt.Errorf("Unexpected error")
+	}, 0, "hello")
+	assert.Equal(t, expectedErr, actualErr)
+	assert.Nil(t, actualBytes)
+	assert.Equal(t, 3, i)
+
+	// Test that 500s are retried.
+	i = 0
+	actualBytes, actualErr = instance.readHttpWithRetries(func(url string) (int, string, io.ReadCloser, error) {
+		assert.Equal(t, "hello", url)
+		i++
+		return 501, "Status", nil, nil
+	}, 0, "hello")
+	assert.Error(t, actualErr)
+	assert.Nil(t, actualBytes)
+	assert.Equal(t, 3, i)
+
+	// Test that 300s are not retried
+	i = 0
+	actualBytes, actualErr = instance.readHttpWithRetries(func(url string) (int, string, io.ReadCloser, error) {
+		assert.Equal(t, "hello", url)
+		i++
+		return 300, "Status", nil, nil
+	}, 0, "hello")
+	assert.Error(t, actualErr)
+	assert.Nil(t, actualBytes)
+	assert.Equal(t, 1, i)
+
+	// Test Success
+	i = 0
+	b := bytes.Buffer{}
+	actualBytes, actualErr = instance.readHttpWithRetries(func(url string) (int, string, io.ReadCloser, error) {
+		assert.Equal(t, "hello", url)
+		i++
+		if i > 1 {
+			return 200, "Status", ioutil.NopCloser(&b), nil
+		}
+		return 501, "Status", nil, nil
+	}, 0, "hello")
+	assert.Nil(t, actualErr)
+	assert.NotNil(t, actualBytes)
+	assert.Equal(t, 2, i)
+}