From 3058e5a49e1da46f6497f64497736bb33986edd2 Mon Sep 17 00:00:00 2001
From: Sam Coe <samcoe@users.noreply.github.com>
Date: Mon, 25 Jul 2022 21:23:08 +0200
Subject: [PATCH] Allow skipping default headers for api clients (#56)

---
 internal/api/http.go      | 28 ++++++++++++++++++++--------
 internal/api/http_test.go | 22 ++++++++++++++++++----
 pkg/api/client.go         |  5 ++++-
 3 files changed, 42 insertions(+), 13 deletions(-)

diff --git a/internal/api/http.go b/internal/api/http.go
index 4104057..9662b5e 100644
--- a/internal/api/http.go
+++ b/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.SkipDefaultHeaders {
+		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}
 }
 
diff --git a/internal/api/http_test.go b/internal/api/http_test.go
index 4384094..64b92bf 100644
--- a/internal/api/http_test.go
+++ b/internal/api/http_test.go
@@ -30,6 +30,7 @@ func TestNewHTTPClient(t *testing.T) {
 		log         *bytes.Buffer
 		host        string
 		headers     map[string]string
+		skipHeaders bool
 		wantHeaders http.Header
 	}{
 		{
@@ -94,6 +95,18 @@ func TestNewHTTPClient(t *testing.T) {
 			host:        "TeSt.CoM",
 			wantHeaders: defaultHeaders(),
 		},
+		{
+			name:        "skips default headers",
+			skipHeaders: 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,
+				SkipDefaultHeaders: tt.skipHeaders,
+				Transport:          reflectHTTP,
 			}
 			if tt.enableLog {
 				opts.Log = tt.log
diff --git a/pkg/api/client.go b/pkg/api/client.go
index 4a4eccc..a31dbca 100644
--- a/pkg/api/client.go
+++ b/pkg/api/client.go
@@ -27,7 +27,7 @@ type ClientOptions struct {
 	EnableCache bool
 
 	// Headers are the headers that will be sent with every API request.
-	// Default headers set are Accept, Authorization, Content-Type, Time-Zone, and User-Agent.
+	// Default headers set are Accept, Content-Type, Time-Zone, and User-Agent.
 	// Default headers will be overridden by keys specified in Headers.
 	Headers map[string]string
 
@@ -38,6 +38,9 @@ type ClientOptions struct {
 	// Default is no logging.
 	Log io.Writer
 
+	// SkipDefaultHeaders disables setting of the default headers.
+	SkipDefaultHeaders bool
+
 	// Timeout specifies a time limit for each API request.
 	// Default is no timeout.
 	Timeout time.Duration