Ensure clientTracer closes http.headers span (#912)

Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>

CHANGELOG.md

@@ -23,6 +23,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 - The B3 Single Header name is now correctly `b3` instead of the previous `X-B3`. (#881)
 - Ensure span status is not set to `Unknown` when no HTTP status code is provided as it is assumed to be `200 OK`. (#908)
+- Ensure `httptrace.clientTracer` closes `http.headers` span. (#912)
 
 ## [0.7.0] - 2020-06-26
 

instrumentation/httptrace/clienttrace.go

@@ -203,6 +203,9 @@ func (ct *clientTracer) wroteHeaderField(k string, v []string) {
 }
 
 func (ct *clientTracer) wroteHeaders() {
+	if ct.span("http.headers") != nil {
+		ct.end("http.headers", nil)
+	}
 	ct.start("http.send", "http.send")
 }
 

instrumentation/httptrace/clienttrace_test.go

@@ -121,6 +121,10 @@ func TestHTTPRequestWithClientTrace(t *testing.T) {
 			name:   "http.receive",
 			parent: "test",
 		},
+		{
+			name:   "http.headers",
+			parent: "test",
+		},
 		{
 			name:   "http.send",
 			parent: "test",