Module docstrings in 3.7 are not part of Module node anymore

Fixes pytest-dev#3530

changelog/3530.trivial.rst

@@ -0,0 +1 @@
+Fix if in tests to support 3.7.0b5, where a docstring handling in AST got reverted.

testing/test_assertrewrite.py

@@ -65,15 +65,30 @@ def getmsg(f, extra_ns=None, must_pass=False):
  pytest.fail("function didn't raise at all")
 
 
+def python_version_has_docstring_in_module_node():
+ """Module docstrings in 3.8 are part of Module node.
+ This was briefly in 3.7 as well but got reverted in beta 5.
+
+ TODO:
+
+ We have a complicated sys.version_info if in here to ease testing on
+ various Python 3.7 versions, but we should remove the 3.7 check after
+ 3.7 is released as stable to make this check more straightforward.
+ """
+ return (
+ sys.version_info < (3, 8) or (3, 7) <= sys.version_info <= (3, 7, 0, "beta", 4)
+ )
+
+
 class TestAssertionRewrite(object):
 
  def test_place_initial_imports(self):
  s = """'Doc string'\nother = stuff"""
  m = rewrite(s)
- # Module docstrings in 3.7 are part of Module node, it's not in the body
- # so we remove it so the following body items have the same indexes on
- # all Python versions
- if sys.version_info < (3, 7):
+ # Module docstrings in some new Python versions are part of Module node
+ # It's not in the body so we remove it so the following body items have
+ # the same indexes on all Python versions:
+ if python_version_has_docstring_in_module_node():
  assert isinstance(m.body[0], ast.Expr)
  assert isinstance(m.body[0].value, ast.Str)
  del m.body[0]
@@ -92,7 +107,7 @@ def test_place_initial_imports(self):
  assert isinstance(m.body[3], ast.Expr)
  s = """'doc string'\nfrom __future__ import with_statement"""
  m = rewrite(s)
- if sys.version_info < (3, 7):
+ if python_version_has_docstring_in_module_node():
  assert isinstance(m.body[0], ast.Expr)
  assert isinstance(m.body[0].value, ast.Str)
  del m.body[0]
@@ -103,7 +118,7 @@ def test_place_initial_imports(self):
  assert imp.col_offset == 0
  s = """'doc string'\nfrom __future__ import with_statement\nother"""
  m = rewrite(s)
- if sys.version_info < (3, 7):
+ if python_version_has_docstring_in_module_node():
  assert isinstance(m.body[0], ast.Expr)
  assert isinstance(m.body[0].value, ast.Str)
  del m.body[0]
@@ -124,7 +139,7 @@ def test_place_initial_imports(self):
  def test_dont_rewrite(self):
  s = """'PYTEST_DONT_REWRITE'\nassert 14"""
  m = rewrite(s)
- if sys.version_info < (3, 7):
+ if python_version_has_docstring_in_module_node():
  assert len(m.body) == 2
  assert isinstance(m.body[0], ast.Expr)
  assert isinstance(m.body[0].value, ast.Str)