Cleanup tests/test_system.c. NFC (#17494)

- Rename to `test_system.c`
- Use `@requires_node`
- Use do_runf to perform test in single call

Author: sbc100

tests/test_browser.py

@@ -5092,7 +5092,7 @@ def test_wasm2js_fallback_on_wasm_compilation_failure(self):
       self.run_browser('test.html', 'hello!', '/report_result?exit:0')
 
   def test_system(self):
-    self.btest_exit(test_file('system.c'))
+    self.btest_exit(test_file('test_system.c'))
 
   # Tests the hello_wasm_worker.c documentation example code.
   @also_with_minimal_runtime

tests/test_other.py

@@ -8846,10 +8846,9 @@ def test_node_js_pthread_module(self):
     self.assertContained('hello, world!', ret)
 
   @no_windows('node system() does not seem to work, see https://github.com/emscripten-core/emscripten/pull/10547')
-  def test_node_js_system(self):
-    self.run_process([EMCC, '-DENV_NODE', test_file('system.c'), '-o', 'a.js', '-O3'])
-    ret = self.run_process(config.NODE_JS + ['a.js'], stdout=PIPE).stdout
-    self.assertContained('OK', ret)
+  @requires_node
+  def test_system_node_js(self):
+    self.do_runf(test_file('test_system.c'), 'Hello from echo', emcc_args=['-DENV_NODE'])
 
   def test_node_eval(self):
     self.run_process([EMCC, '-sENVIRONMENT=node', test_file('hello_world.c'), '-o', 'a.js', '-O3'])

tests/system.c renamed to tests/test_system.c

@@ -21,7 +21,7 @@ int main(void) {
   assert(system("false") == _W_EXITCODE(1, 0));
   assert(system("true") == _W_EXITCODE(0, 0));
   assert(system("kill $$") == _W_EXITCODE(0, 15));
-  system("echo OK");
+  system("echo Hello from echo");
 #else
   assert(system(NULL) == 0);
   assert(system("") == -1);