test(pkg/kube/roundtripper): Add unit tests for roundtripper.go

Signed-off-by: Pavani Pogula <pogulapavani@gmail.com>

pkg/kube/roundtripper_test.go

@@ -0,0 +1,161 @@
+/*
+Copyright The Helm 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 kube
+
+import (
+	"encoding/json"
+	"errors"
+	"io"
+	"net/http"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type fakeRoundTripper struct {
+	resp  *http.Response
+	err   error
+	calls int
+}
+
+func (f *fakeRoundTripper) RoundTrip(_ *http.Request) (*http.Response, error) {
+	f.calls++
+	return f.resp, f.err
+}
+
+func newRespWithBody(statusCode int, contentType, body string) *http.Response {
+	return &http.Response{
+		StatusCode: statusCode,
+		Header:     http.Header{"Content-Type": []string{contentType}},
+		Body:       io.NopCloser(strings.NewReader(body)),
+	}
+}
+
+func TestRetryingRoundTripper_RoundTrip(t *testing.T) {
+	marshalErr := func(code int, msg string) string {
+		b, _ := json.Marshal(kubernetesError{
+			Code:    code,
+			Message: msg,
+		})
+		return string(b)
+	}
+
+	tests := []struct {
+		name          string
+		resp          *http.Response
+		err           error
+		expectedCalls int
+		expectedErr   string
+		expectedCode  int
+	}{
+		{
+			name:          "no retry, status < 500 returns response",
+			resp:          newRespWithBody(200, "application/json", `{"message":"ok","code":200}`),
+			err:           nil,
+			expectedCalls: 1,
+			expectedCode:  200,
+		},
+		{
+			name:          "error from wrapped RoundTripper propagates",
+			resp:          nil,
+			err:           errors.New("wrapped error"),
+			expectedCalls: 1,
+			expectedErr:   "wrapped error",
+		},
+		{
+			name:          "no retry, content-type not application/json",
+			resp:          newRespWithBody(500, "text/plain", "server error"),
+			err:           nil,
+			expectedCalls: 1,
+			expectedCode:  500,
+		},
+		{
+			name: "error reading body returns error",
+			resp: &http.Response{
+				StatusCode: http.StatusInternalServerError,
+				Header:     http.Header{"Content-Type": []string{"application/json"}},
+				Body:       &errReader{},
+			},
+			err:           nil,
+			expectedCalls: 1,
+			expectedErr:   "read error",
+		},
+		{
+			name:          "error decoding JSON returns error",
+			resp:          newRespWithBody(500, "application/json", `invalid-json`),
+			err:           nil,
+			expectedCalls: 1,
+			expectedErr:   "invalid character",
+		},
+		{
+			name:          "retry on etcdserver leader changed message",
+			resp:          newRespWithBody(500, "application/json", marshalErr(500, "some error etcdserver: leader changed")),
+			err:           nil,
+			expectedCalls: 2,
+			expectedCode:  500,
+		},
+		{
+			name:          "retry on raft proposal dropped message",
+			resp:          newRespWithBody(500, "application/json", marshalErr(500, "rpc error: code = Unknown desc = raft proposal dropped")),
+			err:           nil,
+			expectedCalls: 2,
+			expectedCode:  500,
+		},
+		{
+			name:          "no retry on other error message",
+			resp:          newRespWithBody(500, "application/json", marshalErr(500, "other server error")),
+			err:           nil,
+			expectedCalls: 1,
+			expectedCode:  500,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			fakeRT := &fakeRoundTripper{
+				resp: tt.resp,
+				err:  tt.err,
+			}
+			rt := RetryingRoundTripper{
+				Wrapped: fakeRT,
+			}
+			req, _ := http.NewRequest(http.MethodGet, "http://example.com", nil)
+			resp, err := rt.RoundTrip(req)
+
+			if tt.expectedErr != "" {
+				assert.Error(t, err)
+				assert.Contains(t, err.Error(), tt.expectedErr)
+				return
+			}
+			assert.NoError(t, err)
+
+			assert.Equal(t, tt.expectedCode, resp.StatusCode)
+			assert.Equal(t, tt.expectedCalls, fakeRT.calls)
+		})
+	}
+}
+
+type errReader struct{}
+
+func (e *errReader) Read(_ []byte) (int, error) {
+	return 0, errors.New("read error")
+}
+
+func (e *errReader) Close() error {
+	return nil
+}