create tests for a valid and an invalid BOM

both fail with the current implementation

Author: chris-eibl

Lib/test/test_launcher.py

@@ -271,7 +271,10 @@ def py_ini(self, content):
     @contextlib.contextmanager
     def script(self, content, encoding="utf-8"):
         file = Path(tempfile.mktemp(dir=os.getcwd()) + ".py")
-        file.write_text(content, encoding=encoding)
+        if isinstance(content, bytes):
+            file.write_bytes(content)
+        else:
+            file.write_text(content, encoding=encoding)
         try:
             yield file
         finally:
@@ -624,6 +627,25 @@ def test_py_shebang_short_argv0(self):
         self.assertEqual("3.100", data["SearchInfo.tag"])
         self.assertEqual(f'X.Y.exe -prearg "{script}" -postarg', data["stdout"].strip())
 
+    def test_py_shebang_valid_bom(self):
+        with self.py_ini(TEST_PY_DEFAULTS):
+            content = "#! /usr/bin/python -prearg".encode("utf-8")
+            with self.script(b"\xEF\xBB\xBF" + content) as script:
+                data = self.run_py([script, "-postarg"])
+        self.assertEqual("PythonTestSuite", data["SearchInfo.company"])
+        self.assertEqual("3.100", data["SearchInfo.tag"])
+        self.assertEqual(f"X.Y.exe -prearg {quote(script)} -postarg", data["stdout"].strip())
+
+    def test_py_shebang_invalid_bom(self):
+        with self.py_ini(TEST_PY_DEFAULTS):
+            content = "#! /usr/bin/python3 -prearg".encode("utf-8")
+            with self.script(b"\xEF\xAA\xBF" + content) as script:
+                data = self.run_py([script, "-postarg"])
+        self.assertIn("Invalid BOM", data["stderr"])
+        self.assertEqual("PythonTestSuite", data["SearchInfo.company"])
+        self.assertEqual("3.100", data["SearchInfo.tag"])
+        self.assertEqual(f"X.Y.exe {quote(script)} -postarg", data["stdout"].strip())
+
     def test_py_handle_64_in_ini(self):
         with self.py_ini("\n".join(["[defaults]", "python=3.999-64"])):
             # Expect this to fail, but should get oldStyleTag flipped on