fix IsolatedAsyncioTestCase import error on python 3.7

.github/workflows/ci.yml

@@ -25,7 +25,7 @@ jobs:
     - name: Install packages
       run: |
         export PYTHONIOENCODING=UTF8
-        pip install coveralls pytest-cov ptyprocess
+        pip install -r requirements-testing.txt
 
     - name: Run tests
       run: |

requirements-testing.txt

@@ -1,4 +1,6 @@
-pytest
-pytest-cov
+aiounittest; python_version < '3.8'
 coverage
 coveralls
+ptyprocess
+pytest
+pytest-cov

tests/PexpectTestCase.py

@@ -26,6 +26,11 @@
 import sys
 import os
 
+try:
+    from unittest import IsolatedAsyncioTestCase
+except ImportError:
+    from aiounittest import AsyncTestCase as IsolatedAsyncioTestCase
+
 
 class _PexpectTestCaseBase:
     def setUp(self):
@@ -115,5 +120,5 @@ class PexpectTestCase(_PexpectTestCaseBase, unittest.TestCase):
     pass
 
 
-class AsyncPexpectTestCase(_PexpectTestCaseBase, unittest.IsolatedAsyncioTestCase):
+class AsyncPexpectTestCase(_PexpectTestCaseBase, IsolatedAsyncioTestCase):
     pass