Allow skipping option and header resolution for api clients

example_gh_test.go

@@ -125,3 +125,33 @@ func ExampleCurrentRepository() {
 	}
 	fmt.Printf("%s/%s/%s\n", repo.Host(), repo.Owner(), repo.Name())
 }
+
+// Example of using SkipResolution option to change a http.Client
+// into a api.RESTClient.
+func ExampleSkipResolution() {
+	host := "github.com"
+	httpOpts := api.ClientOptions{
+		Host: host,
+	}
+	httpClient, err := HTTPClient(&httpOpts)
+	if err != nil {
+		log.Fatal(err)
+	}
+	// Use SkipResolution as our http.Client does the handling of
+	// options and headers.
+	restOpts := api.ClientOptions{
+		SkipResolution: true,
+		Host:           host,
+		Transport:      httpClient.Transport,
+	}
+	restClient, err := RESTClient(&restOpts)
+	if err != nil {
+		log.Fatal(err)
+	}
+	response := []struct{ Name string }{}
+	err = restClient.Get("repos/cli/cli/tags", &response)
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Println(response)
+}

gh.go

@@ -141,6 +141,9 @@ func CurrentRepository() (repo.Repository, error) {
 }
 
 func optionsNeedResolution(opts *api.ClientOptions) bool {
+	if opts.SkipResolution {
+		return false
+	}
 	if opts.Host == "" {
 		return true
 	}

gh_test.go

@@ -262,6 +262,13 @@ func TestOptionsNeedResolution(t *testing.T) {
 			},
 			out: true,
 		},
+		{
+			name: "SkipResolution specified",
+			opts: &api.ClientOptions{
+				SkipResolution: true,
+			},
+			out: false,
+		},
 	}
 
 	for _, tt := range tests {

internal/api/http.go

@@ -112,6 +112,12 @@ func NewHTTPClient(opts *api.ClientOptions) http.Client {
 		transport = logger.RoundTripper(transport)
 	}
 
+	if opts.Headers == nil {
+		opts.Headers = map[string]string{}
+	}
+	if !opts.SkipResolution {
+		resolveHeaders(opts.Headers)
+	}
 	transport = newHeaderRoundTripper(opts.Host, opts.AuthToken, opts.Headers, transport)
 
 	return http.Client{Transport: transport, Timeout: opts.Timeout}
@@ -148,10 +154,7 @@ type headerRoundTripper struct {
 	rt      http.RoundTripper
 }
 
-func newHeaderRoundTripper(host string, authToken string, headers map[string]string, rt http.RoundTripper) http.RoundTripper {
-	if headers == nil {
-		headers = map[string]string{}
-	}
+func resolveHeaders(headers map[string]string) {
 	if _, ok := headers[contentType]; !ok {
 		headers[contentType] = jsonContentType
 	}
@@ -167,11 +170,11 @@ func newHeaderRoundTripper(host string, authToken string, headers map[string]str
 			}
 		}
 	}
-	if _, ok := headers[authorization]; !ok && authToken != "" {
-		headers[authorization] = fmt.Sprintf("token %s", authToken)
-	}
 	if _, ok := headers[timeZone]; !ok {
-		headers[timeZone] = currentTimeZone()
+		tz := currentTimeZone()
+		if tz != "" {
+			headers[timeZone] = tz
+		}
 	}
 	if _, ok := headers[accept]; !ok {
 		// Preview for PullRequest.mergeStateStatus.
@@ -180,6 +183,15 @@ func newHeaderRoundTripper(host string, authToken string, headers map[string]str
 		a += ", application/vnd.github.nebula-preview"
 		headers[accept] = a
 	}
+}
+
+func newHeaderRoundTripper(host string, authToken string, headers map[string]string, rt http.RoundTripper) http.RoundTripper {
+	if _, ok := headers[authorization]; !ok && authToken != "" {
+		headers[authorization] = fmt.Sprintf("token %s", authToken)
+	}
+	if len(headers) == 0 {
+		return rt
+	}
 	return headerRoundTripper{host: host, headers: headers, rt: rt}
 }
 

internal/api/http_test.go

@@ -25,12 +25,13 @@ func TestNewHTTPClient(t *testing.T) {
 	}
 
 	tests := []struct {
-		name        string
-		enableLog   bool
-		log         *bytes.Buffer
-		host        string
-		headers     map[string]string
-		wantHeaders http.Header
+		name           string
+		enableLog      bool
+		log            *bytes.Buffer
+		host           string
+		headers        map[string]string
+		skipResolution bool
+		wantHeaders    http.Header
 	}{
 		{
 			name:        "sets default headers",
@@ -94,6 +95,18 @@ func TestNewHTTPClient(t *testing.T) {
 			host:        "TeSt.CoM",
 			wantHeaders: defaultHeaders(),
 		},
+		{
+			name:           "skips resolving headers",
+			skipResolution: true,
+			wantHeaders: func() http.Header {
+				h := defaultHeaders()
+				h.Del(accept)
+				h.Del(contentType)
+				h.Del(timeZone)
+				h.Del(userAgent)
+				return h
+			}(),
+		},
 	}
 
 	for _, tt := range tests {
@@ -102,10 +115,11 @@ func TestNewHTTPClient(t *testing.T) {
 				tt.host = "test.com"
 			}
 			opts := api.ClientOptions{
-				Host:      tt.host,
-				AuthToken: "oauth_token",
-				Headers:   tt.headers,
-				Transport: reflectHTTP,
+				Host:           tt.host,
+				AuthToken:      "oauth_token",
+				Headers:        tt.headers,
+				SkipResolution: tt.skipResolution,
+				Transport:      reflectHTTP,
 			}
 			if tt.enableLog {
 				opts.Log = tt.log

pkg/api/client.go

@@ -38,6 +38,12 @@ type ClientOptions struct {
 	// Default is no logging.
 	Log io.Writer
 
+	// SkipResolution disables all automatic resolution of options and headers.
+	// This option is best used in conjunction with the Transport option,
+	// where the Transport mechanism already provides the necessary information
+	// for interacting with the API.
+	SkipResolution bool
+
 	// Timeout specifies a time limit for each API request.
 	// Default is no timeout.
 	Timeout time.Duration