fix: golang server replay edge case, response body is empty.

internal/README.md

@@ -0,0 +1,116 @@
+# Development Guide: Testing Local test-server Changes
+
+## Overview
+This guide outlines the standard procedure for compiling and testing local modifications to the Go test-server. The test-server is a Go application distributed via language-specific SDK wrappers for ease of adoption.
+
+The recommended workflow for end-to-end validation is to test through the SDK sample. This ensures that any changes to the core Go binary are compatible with the SDK integration layer.
+
+## Step-by-Step e2e Testing Workflow with TypeScript SDK
+
+The process involves compiling your local Go source code, preparing the TypeScript environment, and then linking your new binary to the sample project for testing.
+
+Step 1: Compile the Go Binary
+
+First, compile your local changes into an executable test-server binary.
+
+Navigate to the project's root directory (`test-server`) and build the Go application.
+
+```sh
+go build
+```
+
+After a successful build, a new executable named `test-server` will be present in the root directory.
+
+Step 2: Build the TypeScript SDK Wrapper
+
+The TypeScript SDK acts as a wrapper around the Go binary. It must be built before we can use it in the TypeScript samples.
+
+Navigate to the TypeScript SDK directory: `test-server/sdks/typescript`.
+
+Install dependencies and build the SDK package.
+
+```sh
+npm install
+npm run build
+```
+
+Step 3: Prepare the Sample Test Project
+
+The sample project consumes the TypeScript SDK. We will set it up to run our tests.
+
+Navigate to the sample project directory: `test-server/sdks/typescript/samples`.
+
+Install its dependencies. This command installs the test-server-sdk we just built in step 2.
+
+```sh
+npm install
+```
+
+Step 4: Link Your Local test-server Binary
+This is the most critical step. You must replace the pre-packaged binary in the sample project's dependencies with the custom binary you built in Step 1.
+
+After the previous steps, the directory structure looks like this. The goal is to replace the test-server binary highlighted below, the graph below is a tree view of your directory structure from `test-server/sdks/typescript/samples`.
+
+```diff
+├── dist
+│   └── specs
+│   ├── sample.spec.js
+│   └── sample.spec.js.map
+├── jasmine.json
+├── node_modules
+│   ├── ... (other packages hidden)
+│   ├── test-server-sdk
+│   │   ├── bin
+│   │   │   ├── CHANGELOG.md
+│   │   │   ├── LICENSE
+│   │   │   ├── README.md
++│  │   │   └── test-server
+│   │   ├── checksums.json
+│   │   ├── LICENSE
+│   │   ├── package.json
+│   │   └── postinstall.js
+│   └── ... (other packages hidden)
+├── package.json
+├── package-lock.json
+├── src
+│   └── specs
+│   └── sample.spec.ts
+├── test-data
+│   ├── config
+│   │   └── test-server-config.yml
+│   └── recordings
+└── tsconfig.json
+
+```
+
+From the `test-server/sdks/typescript/samples` directory, run the following command to move your freshly compiled binary into place, overwriting the old one.
+
+```sh
+
+# Move the test-server binary from the project root to the samples' node_modules directory.
+mv ../../../test-server ./node_modules/test-server-sdk/bin/test-server
+```
+
+Step 5: Run the Integration Tests
+
+You are now ready to run the sample project's test suite against your local test-server build.
+
+From the `test-server/sdks/typescript/samples` directory:
+
+To run tests in playback mode:
+
+```sh
+#To run tests in replay mode:
+npm run test
+#To run tests in record mode (and regenerate test recordings):
+npm run test:record
+```
+
+Any output or errors from the test run will now reflect the behavior of your local test-server changes.
+
+You should also see the actual command run like this:
+
+```
+[test-server-sdk] Starting test-server in 'replay' mode. Command: /usr/local/google/home/test-server/sdks/typescript/sample/node_modules/test-server-sdk/bin/test-server replay --config /usr/local/google/home/wanlindu/test-server/sdks/typescript/sample/test-data/config/test-server-config.yml --recording-dir /usr/local/google/home/wanlindu/test-server/sdks/typescript/sample/test-data/recordings
+```
+You can cross check if you have used the binary you just provided.

internal/replay/replay_http_server.go

@@ -178,6 +178,11 @@ func (r *ReplayHTTPServer) writeResponse(w http.ResponseWriter, resp *store.Reco
 		w.Header().Add(key, value)
 	}
 
+	// When the response body is empty we return directly with the headers.
+	if len(resp.BodySegments) == 0 {
+		return nil
+	}
+
 	w.WriteHeader(int(resp.StatusCode))
 
 	if !strings.Contains(req.URL, "alt=sse") {

sdks/typescript/sample/src/specs/sample.spec.ts

@@ -59,8 +59,8 @@ describe('Sample Test Suite (with test-server)', () => {
                 });
 
                 res.on('end', () => {
-                    expect(data.toLowerCase()).toContain('github');
-                    console.log('[SampleSpec] Received response, content check passed (basic).');
+                    expect(JSON.stringify(res.headers)).toContain('github');
+                    console.log('[SampleSpec] Received response. Because the body of the response can be empty, test headers instead.');
                     resolve();
                 });
             });