refactor: remove code that was only needed for Python 3.6

Author: nedbat

coverage/env.py

@@ -57,18 +57,6 @@ class PYBEHAVIOR:
     # Can co_lnotab have negative deltas?
     negative_lnotab = not (PYPY and PYPYVERSION < (7, 2))
 
-    # Do .pyc files conform to PEP 552? Hash-based pyc's.
-    hashed_pyc_pep552 = (PYVERSION >= (3, 7, 0, 'alpha', 4))
-
-    # Python 3.7.0b3 changed the behavior of the sys.path[0] entry for -m. It
-    # used to be an empty string (meaning the current directory). It changed
-    # to be the actual path to the current directory, so that os.chdir wouldn't
-    # affect the outcome.
-    actual_syspath0_dash_m = (
-        (CPYTHON and (PYVERSION >= (3, 7, 0, 'beta', 3))) or
-        (PYPY and (PYPYVERSION >= (7, 3, 4)))
-        )
-
     # 3.7 changed how functions with only docstrings are numbered.
     docstring_only_function = (not PYPY) and ((3, 7, 0, 'beta', 5) <= PYVERSION <= (3, 10))
 

coverage/execfile.py

@@ -80,10 +80,7 @@ def prepare(self):
         This needs to happen before any importing, and without importing anything.
         """
         if self.as_module:
-            if env.PYBEHAVIOR.actual_syspath0_dash_m:
-                path0 = os.getcwd()
-            else:
-                path0 = ""
+            path0 = os.getcwd()
         elif os.path.isdir(self.arg0):
             # Running a directory means running the __main__.py file in that
             # directory.
@@ -295,18 +292,14 @@ def make_code_from_pyc(filename):
         if magic != PYC_MAGIC_NUMBER:
             raise NoCode(f"Bad magic number in .pyc file: {magic!r} != {PYC_MAGIC_NUMBER!r}")
 
-        date_based = True
-        if env.PYBEHAVIOR.hashed_pyc_pep552:
-            flags = struct.unpack('<L', fpyc.read(4))[0]
-            hash_based = flags & 0x01
-            if hash_based:
-                fpyc.read(8)    # Skip the hash.
-                date_based = False
-        if date_based:
+        flags = struct.unpack('<L', fpyc.read(4))[0]
+        hash_based = flags & 0x01
+        if hash_based:
+            fpyc.read(8)    # Skip the hash.
+        else:
             # Skip the junk in the header that we don't need.
-            fpyc.read(4)            # Skip the moddate.
-            # 3.3 added another long to the header (size), skip it.
-            fpyc.read(4)
+            fpyc.read(4)    # Skip the moddate.
+            fpyc.read(4)    # Skip the size.
 
         # The rest of the file is the code object we want.
         code = marshal.load(fpyc)

tests/test_execfile.py

@@ -242,7 +242,6 @@ def test_running_pyc_from_wrong_python(self):
         # In some environments, the pycfile persists and pollutes another test.
         os.remove(pycfile)
 
-    @pytest.mark.skipif(not env.PYBEHAVIOR.hashed_pyc_pep552, reason="No hashed .pyc here")
     def test_running_hashed_pyc(self):
         pycfile = self.make_pyc(invalidation_mode=py_compile.PycInvalidationMode.CHECKED_HASH)
         run_python_file([pycfile])