diff --git a/src/tests/test_cases/fstrings.py36 b/src/tests/test_cases/fstrings.py36
deleted file mode 100644
index 9d4243cb..00000000
--- a/src/tests/test_cases/fstrings.py36
+++ /dev/null
@@ -1,11 +0,0 @@
-"""Test for warning about f-strings as docstrings."""
-
-from .expected import Expectation
-
-expectation = Expectation()
-expect = expectation.expect
-
-
-@expect("D303: f-strings are not valid as docstrings")
-def fstring():
-    f"""Toggle the gizmo."""
diff --git a/src/tests/test_definitions.py b/src/tests/test_definitions.py
index 4e9accb3..3971f0a0 100644
--- a/src/tests/test_definitions.py
+++ b/src/tests/test_definitions.py
@@ -1,8 +1,6 @@
 """Old parser tests."""
 
-import sys
 import os
-import os.path
 import re
 import pytest
 from pydocstyle.violations import Error, ErrorRegistry
@@ -26,41 +24,17 @@
     'canonical_numpy_examples',
     'canonical_pep257_examples',
 ])
-def test_all_interpreters(test_case):
-    """Complex test cases that run under all interpreters."""
-    run_case(test_case)
-
-
-@pytest.mark.skipif(
-    sys.version_info < (3, 6),
-    reason="f-string support needed"
-)
-def test_fstrings():
-    """Run the f-string test case under Python 3.6+ only."""
-    # When run under Python 3.5, mypy reports a parse error for the test file,
-    # because Python 3.5 doesn't support f-strings. It does not support
-    # ignoring parse errors.
-    #
-    # To work around this, we put our code in a file that mypy cannot see. This
-    # code reveals it to Python.
-    from . import test_cases
-    import importlib.machinery
-    test_cases_dir = test_cases.__path__[0]
-    loader = sys.path_importer_cache[test_cases_dir]
-    loader._loaders.append(('.py36', importlib.machinery.SourceFileLoader))
-
-    run_case('fstrings')
-
-
-def run_case(test_case):
+def test_complex_file(test_case):
     """Run domain-specific tests from test.py file."""
     case_module = __import__(f'test_cases.{test_case}',
                              globals=globals(),
                              locals=locals(),
                              fromlist=['expectation'],
                              level=1)
-
-    test_case_file = os.path.relpath(case_module.__file__)
+    test_case_dir = os.path.normcase(os.path.dirname(__file__))
+    test_case_file = os.path.join(test_case_dir,
+                                  'test_cases',
+                                  test_case + '.py')
     results = list(check([test_case_file],
                          select=set(ErrorRegistry.get_error_codes()),
                          ignore_decorators=re.compile(