Module docstrings in 3.7 are not part of Module node anymore

Fixes #3530

Author: hroncok

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

@@ -70,10 +70,18 @@ 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
+        # Module docstrings in 3.8 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):
+        # 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
+        if (
+            sys.version_info < (3, 8)
+            or (3, 7) <= sys.version_info <= (3, 7, 0, "beta", 4)
+        ):
             assert isinstance(m.body[0], ast.Expr)
             assert isinstance(m.body[0].value, ast.Str)
             del m.body[0]
@@ -92,7 +100,10 @@ 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 (
+            sys.version_info < (3, 8)
+            or (3, 7) <= sys.version_info <= (3, 7, 0, "beta", 4)
+        ):
             assert isinstance(m.body[0], ast.Expr)
             assert isinstance(m.body[0].value, ast.Str)
             del m.body[0]
@@ -103,7 +114,10 @@ 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 (
+            sys.version_info < (3, 8)
+            or (3, 7) <= sys.version_info <= (3, 7, 0, "beta", 4)
+        ):
             assert isinstance(m.body[0], ast.Expr)
             assert isinstance(m.body[0].value, ast.Str)
             del m.body[0]
@@ -124,7 +138,10 @@ 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 (
+            sys.version_info < (3, 8)
+            or (3, 7) <= sys.version_info <= (3, 7, 0, "beta", 4)
+        ):
             assert len(m.body) == 2
             assert isinstance(m.body[0], ast.Expr)
             assert isinstance(m.body[0].value, ast.Str)