Include trailers in server Send events

Author: pimterry

src/client/client-types.ts

@@ -3,6 +3,7 @@ import type * as Mockttp from 'mockttp';
 // --- Request definition types ---
 
 export type RawHeaders = Mockttp.RawHeaders;
+export type RawTrailers = Mockttp.RawTrailers;
 
 export interface RequestDefinition {
     method: string;
@@ -87,6 +88,7 @@ export type ResponseStreamEvents =
     | RequestStart
     | ResponseHead
     | ResponseBodyPart
+    | ResponseTrailers
     | ResponseEnd;
 // Other notable event is errors (via 'error' event)
 
@@ -110,6 +112,12 @@ export interface ResponseBodyPart {
     timestamp: number;
 }
 
+export interface ResponseTrailers {
+    type: 'response-trailers';
+    trailers: RawTrailers;
+    timestamp: number;
+}
+
 export interface ResponseEnd {
     type: 'response-end';
     timestamp: number;

src/client/http-client.ts

@@ -163,6 +163,13 @@ export class HttpClient {
             }));
 
             response.on('end', () => {
+                if (response.rawTrailers?.length) {
+                    resultsStream.push({
+                        type: 'response-trailers',
+                        trailers: pairFlatRawHeaders(response.rawTrailers),
+                        timestamp: performance.now()
+                    });
+                }
                 resultsStream.push({ type: 'response-end', timestamp: performance.now() });
                 resultsStream.push(null);
             });

test/unit/send-request.spec.ts

@@ -27,7 +27,11 @@ describe("The HTTP client API", () => {
             return {
                 statusCode: 200,
                 statusMessage: 'Custom status message',
-                headers: { 'custom-HEADER': 'custom-VALUE' },
+                headers: {
+                    'custom-HEADER': 'custom-VALUE',
+                    'Transfer-Encoding': 'chunked'
+                },
+                trailers: { 'custom-TRAILER': 'trailer-VALUE' },
                 rawBody: Buffer.from('Mock response body')
             };
         });
@@ -46,7 +50,7 @@ describe("The HTTP client API", () => {
 
         const responseEvents = await streamToArray<any>(responseStream);
 
-        expect(responseEvents.length).to.equal(4);
+        expect(responseEvents.length).to.equal(5);
         expect(_.omit(responseEvents[0], 'timestamp', 'startTime')).to.deep.equal({
             type: 'request-start'
         });
@@ -55,13 +59,22 @@ describe("The HTTP client API", () => {
             statusCode: 200,
             statusMessage: 'Custom status message',
             headers: [
-                ['custom-HEADER', 'custom-VALUE']
+                ['custom-HEADER', 'custom-VALUE'],
+                ['Transfer-Encoding', 'chunked']
             ]
         });
 
         expect(responseEvents[2].type).equal('response-body-part');
         expect(responseEvents[2].rawBody.toString()).to.equal('Mock response body');
+
         expect(_.omit(responseEvents[3], 'timestamp')).to.deep.equal({
+            type: 'response-trailers',
+            trailers: [
+                ['custom-TRAILER', 'trailer-VALUE']
+            ]
+        });
+
+        expect(_.omit(responseEvents[4], 'timestamp')).to.deep.equal({
             type: 'response-end'
         });
     });