[testing] Use customizable port for the browser test server. (#24976)

Add a helper to copy `browser_reporting.js` file with the test server
URL inlined. We could do `globalThis.location` for some tests, but that
doesn't work for audio worklets and when using blob urls.

Where possible just remove the reference to `http:://localhost:8888` and
use `/`.

Author: brendandahl

test/browser/async_bad_list.cpp

@@ -17,7 +17,7 @@ int main() {
         Module.reported = true;
         console.log("reporting success");
         // manually REPORT_RESULT; we shouldn't call back into native code at this point
-        await fetch("http://localhost:8888/report_result?0");
+        await fetch("/report_result?0");
         window.close();
       }
     };

test/browser/async_returnvalue.cpp

@@ -39,7 +39,7 @@ int main() {
         Module.reported = true;
         console.log("reporting success");
         // manually REPORT_RESULT; we shouldn't call back into native code at this point
-        await fetch("http://localhost:8888/report_result?0");
+        await fetch("/report_result?0");
         window.close();
       }
     };

test/browser/test_cwrap_early.js

@@ -9,7 +9,7 @@ Module['preRun'] = () => {
     console.log('onRuntimeInitialized');
     if (wrappedAdd(5, 6) != 11) throw '5 + 6 should be 11';
     // report success
-    await fetch('http://localhost:8888/report_result?0');
+    await fetch('/report_result?0');
     window.close();
   };
 };

test/browser_reporting.js

@@ -3,7 +3,7 @@ var captureStdio = false;
 
 var hasModule = typeof Module === 'object' && Module;
 
-var reportingURL = 'http://localhost:8888';
+var reportingURL = '{{{REPORTING_URL}}}';
 
 async function reportResultToServer(result) {
   if (reportResultToServer.reported) {

test/canvas_style_proxy_shell.html

@@ -153,7 +153,7 @@
 
       window.verifyCanvasStyle = async () => {
         var success = Module.canvas.style.cursor === 'pointer';
-        await fetch('http://localhost:8888/report_result?' + (success ? 1 : 0));
+        await fetch('/report_result?' + (success ? 1 : 0));
         window.close();
       }
 

test/common.py

@@ -2310,7 +2310,8 @@ class BrowserCore(RunnerCore):
   # single test (hundreds of minutes)
   MAX_UNRESPONSIVE_TESTS = 10
   PORT = 8888
-  HARNESS_URL = 'http://localhost:%s/run_harness' % PORT
+  SERVER_URL = f'http://localhost:{PORT}'
+  HARNESS_URL = f'{SERVER_URL}/run_harness'
   BROWSER_TIMEOUT = 60
 
   unresponsive_tests = 0
@@ -2378,6 +2379,11 @@ def tearDownClass(cls):
   def is_browser_test(self):
     return True
 
+  def add_browser_reporting(self):
+    contents = read_file(test_file('browser_reporting.js'))
+    contents = contents.replace('{{{REPORTING_URL}}}', BrowserCore.SERVER_URL)
+    create_file('browser_reporting.js', contents)
+
   def assert_out_queue_empty(self, who):
     if not self.harness_out_queue.empty():
       responses = []
@@ -2461,7 +2467,8 @@ def compile_btest(self, filename, cflags, reporting=Reporting.FULL):
     # the header as there may be multiple files being compiled here).
     if reporting != Reporting.NONE:
       # For basic reporting we inject JS helper funtions to report result back to server.
-      cflags += ['--pre-js', test_file('browser_reporting.js')]
+      self.add_browser_reporting()
+      cflags += ['--pre-js', 'browser_reporting.js']
       if reporting == Reporting.FULL:
         # If C reporting (i.e. the REPORT_RESULT macro) is required we
         # also include report_result.c and force-include report_result.h
@@ -2473,6 +2480,9 @@ def compile_btest(self, filename, cflags, reporting=Reporting.FULL):
     if not os.path.exists(filename):
       filename = test_file(filename)
     self.run_process([compiler_for(filename), filename] + self.get_cflags() + cflags)
+    # Remove the file since some tests have assertions for how many files are in
+    # the output directory.
+    utils.delete_file('browser_reporting.js')
 
   def btest_exit(self, filename, assert_returncode=0, *args, **kwargs):
     """Special case of `btest` that reports its result solely via exiting

test/custom_messages_proxy_shell.html

@@ -16,7 +16,7 @@
       function sendResult(success) {
         if (window.sentTestResult) return;
         window.sentTestResult = true;
-        fetch('http://localhost:8888/report_result?' + (success ? 1 : 0))
+        fetch('/report_result?' + (success ? 1 : 0))
           .then(() => window.close());
       }
 

test/emscripten_throw_number_pre.js

@@ -1,5 +1,5 @@
 addEventListener('error', (event) => {
   window.disableErrorReporting = true;
   var result = event.error === 42 ? 0 : 1;
-  fetch('http://localhost:8888/report_result?' + result);
+  fetch('/report_result?' + result);
 });

test/emscripten_throw_string_pre.js

@@ -1,5 +1,5 @@
 addEventListener('error', (event) => {
   window.disableErrorReporting = true;
   var result = event.error === 'Hello!' ? 0 : 1;
-  fetch('http://localhost:8888/report_result?' + result);
+  fetch('/report_result?' + result);
 });

test/fetch/test_fetch_redirect.c

@@ -9,8 +9,6 @@
 #include <stdlib.h>
 #include <emscripten/fetch.h>
 
-#define SERVER "http://localhost:8888"
-
 // 301: Moved Permanently                      - https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/301
 // 302: Found (Previously "Moved Temporarily") - https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/302
 // 303: See Other                              - https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/303