Simplify test_stdin. NFC (#24114)

Author: sbc100

test/common.py

@@ -1499,7 +1499,8 @@ def cleanup(line):
 
   def run_js(self, filename, engine=None, args=None,
              assert_returncode=0,
-             interleaved_output=True):
+             interleaved_output=True,
+             input=None):
     # use files, as PIPE can get too full and hang us
     stdout_file = self.in_dir('stdout')
     stderr_file = None
@@ -1523,7 +1524,8 @@ def run_js(self, filename, engine=None, args=None,
       jsrun.run_js(filename, engine, args,
                    stdout=stdout,
                    stderr=stderr,
-                   assert_returncode=assert_returncode)
+                   assert_returncode=assert_returncode,
+                   input=input)
     except subprocess.TimeoutExpired as e:
       timeout_error = e
     except subprocess.CalledProcessError as e:

test/jsrun.py

@@ -84,7 +84,7 @@ def require_engine(engine):
 
 
 def run_js(filename, engine, args=None,
-           stdin=None, stdout=PIPE, stderr=None, cwd=None,
+           stdin=None, stdout=PIPE, stderr=None, cwd=None, input=None,
            full_output=False, assert_returncode=0, skip_check=False,
            timeout=DEFAULT_TIMEOUT):
   """Execute javascript code generated by tests, with possible timeout."""
@@ -104,6 +104,7 @@ def run_js(filename, engine, args=None,
         stdin=stdin,
         stdout=stdout,
         stderr=stderr,
+        input=input,
         cwd=cwd,
         timeout=timeout,
         universal_newlines=True)

test/test_other.py

@@ -1669,23 +1669,12 @@ def test_export_all_and_exported_functions(self):
     'closure': (['-O2', '--closure=1'],),
   })
   def test_stdin(self, args):
-    create_file('in.txt', 'abcdef\nghijkl\n')
     self.set_setting('ENVIRONMENT', 'node,shell')
     self.emcc(test_file('module/test_stdin.c'), args=args, output_filename='out.js')
 
     for engine in config.JS_ENGINES:
-      engine[0] = os.path.normpath(engine[0])
-      # work around a bug in python's subprocess module
-      # (we'd use self.run_js() normally)
-      delete_file('out.txt')
-      cmd = jsrun.make_command(os.path.normpath('out.js'), engine)
-      cmd = shared.shlex_join(cmd)
-      print(cmd, file=sys.stderr)
-      if WINDOWS:
-        os.system(f'type "in.txt" | {cmd} >out.txt')
-      else: # posix
-        os.system(f'cat in.txt | {cmd} > out.txt')
-      self.assertContained('abcdef\nghijkl\neof', read_file('out.txt'))
+      output = self.run_js('out.js', engine, input='abcdef\nghijkl\n')
+      self.assertContained('abcdef\nghijkl\neof', output)
 
   @crossplatform
   def test_module_stdin(self):