Give test subclasses unique names to avoid race conditions

.github/workflows/test.yml

@@ -8,7 +8,7 @@ jobs:
     strategy:
       max-parallel: 4
       matrix:
-        python-version: [3.5, 3.6, 3.7]
+        python-version: [3.5, 3.6, 3.7, 3.8]
 
     steps:
       - uses: actions/checkout@v1
@@ -33,3 +33,4 @@ jobs:
         run: ci/actions/test
     env:
       RUST_BACKTRACE: 1
+      PYTHONUNBUFFERED: 1

.travis.yml

@@ -24,8 +24,6 @@ matrix:
     - name: PyPy3.5 7.0 # Tested via anaconda PyPy (since travis's PyPy version is too old)
       python: "3.7"
       env: FEATURES="pypy" PATH="$PATH:/opt/anaconda/envs/pypy3/bin"
-  allow_failures:
-    - python: "3.8-dev"
 
 env:
   global:

tests/test_datetime.rs

@@ -15,21 +15,31 @@ fn _get_subclasses<'p>(
 
     let locals = [(py_type, datetime.get(py_type)?)].into_py_dict(*py);
 
-    let make_subclass_py = format!("class Subklass({}):\n    pass", py_type);
+    let subclass_name = format!("Subklass{}", py_type);
+    let make_subclass_py = format!("class {}({}):\n    pass", subclass_name, py_type);
 
-    let make_sub_subclass_py = "class SubSubklass(Subklass):\n    pass";
+    let subsubclass_name = format!("SubSubklass{}", py_type);
+    let make_sub_subclass_py = format!("class {}({}):\n    pass", subsubclass_name, subclass_name);
 
     py.run(&make_subclass_py, None, Some(&locals))?;
+    py.run("print('subclass ok')", None, None)?;
     py.run(&make_sub_subclass_py, None, Some(&locals))?;
+    py.run("print('subsubclass ok')", None, None)?;
 
     // Construct an instance of the base class
     let obj = py.eval(&format!("{}({})", py_type, args), None, Some(&locals))?;
 
     // Construct an instance of the subclass
-    let sub_obj = py.eval(&format!("Subklass({})", args), None, Some(&locals))?;
+    let sub_obj = py.eval(&format!("{}({})", subclass_name, args), None, Some(&locals))?;
+    py.run("print('instance subclass ok')", None, None)?;
 
     // Construct an instance of the sub-subclass
-    let sub_sub_obj = py.eval(&format!("SubSubklass({})", args), None, Some(&locals))?;
+    let sub_sub_obj = py.eval(
+        &format!("{}({})", subsubclass_name, args),
+        None,
+        Some(&locals),
+    )?;
+    py.run("print('instance subsubclass ok')", None, None)?;
 
     Ok((obj, sub_obj, sub_sub_obj))
 }

tox.ini

@@ -2,6 +2,7 @@
 envlist = py35,
           py36,
           py37,
+          py38,
 minversion = 3.4.0
 skip_missing_interpreters = true