Improve automated tests support on Windows

nox/virtualenv.py

@@ -183,10 +183,8 @@ def __init__(
     @property
     def bin(self) -> str:
         """Returns the location of the conda env's bin folder."""
-        if _SYSTEM == "Windows":
-            return os.path.join(self.location, "Scripts")
-        else:
-            return os.path.join(self.location, "bin")
+        bin_folder = "Scripts" if _SYSTEM == "Windows" else "bin"
+        return os.path.join(self.location, bin_folder)
 
     def create(self) -> bool:
         """Create the conda env."""

noxfile.py

@@ -13,6 +13,7 @@
 # limitations under the License.
 
 import os
+import shutil
 
 import nox
 
@@ -37,7 +38,13 @@ def tests(session):
         session.run("pytest", *tests)
         return
     session.run(
-        "pytest", "--cov=nox", "--cov-config", ".coveragerc", "--cov-report=", *tests
+        "pytest",
+        "--cov=nox",
+        "--cov-config",
+        ".coveragerc",
+        "--cov-report=",
+        *tests,
+        env={"COVERAGE_FILE": ".coverage.{}".format(session.python)}
     )
     session.notify("cover")
 
@@ -62,6 +69,7 @@ def cover(session):
         fail_under = "--fail-under=99"
     else:
         fail_under = "--fail-under=100"
+    session.run("coverage", "combine")
     session.run("coverage", "report", fail_under, "--show-missing")
     session.run("coverage", "erase")
 
@@ -90,10 +98,10 @@ def lint(session):
     session.run("flake8", "nox", *files)
 
 
-@nox.session(python="3.8")
+@nox.session(python="3.7")
 def docs(session):
     """Build the documentation."""
-    session.run("rm", "-rf", "docs/_build", external=True)
+    shutil.rmtree("docs/_build", ignore_errors=True)
     session.install("-r", "requirements-test.txt")
     session.install(".")
     session.cd("docs")

tests/test_virtualenv.py

@@ -174,13 +174,18 @@ def test_condaenv_create(make_conda):
     assert dir_.join("test.txt").check()
 
 
-@pytest.mark.skipif(IS_WINDOWS, reason="Not testing multiple interpreters on Windows.")
 @pytest.mark.skipif(not HAS_CONDA, reason="Missing conda command.")
 def test_condaenv_create_interpreter(make_conda):
     venv, dir_ = make_conda(interpreter="3.7")
     venv.create()
-    assert dir_.join("bin", "python").check()
-    assert dir_.join("bin", "python3.7").check()
+    if IS_WINDOWS:
+        assert dir_.join("python.exe").check()
+        assert dir_.join("python37.dll").check()
+        assert dir_.join("python37.pdb").check()
+        assert not dir_.join("python37.exe").check()
+    else:
+        assert dir_.join("bin", "python").check()
+        assert dir_.join("bin", "python3.7").check()
 
 
 @mock.patch("nox.virtualenv._SYSTEM", new="Windows")
@@ -296,12 +301,16 @@ def test_create_venv_backend(make_one):
     venv.create()
 
 
-@pytest.mark.skipif(IS_WINDOWS, reason="Not testing multiple interpreters on Windows.")
 def test_create_interpreter(make_one):
-    venv, dir_ = make_one(interpreter="python3")
+    interpreter = "3.7" if IS_WINDOWS else "python3"
+    venv, dir_ = make_one(interpreter=interpreter)
     venv.create()
-    assert dir_.join("bin", "python").check()
-    assert dir_.join("bin", "python3").check()
+    if IS_WINDOWS:
+        assert dir_.join("Scripts", "python.exe").check()
+        assert not dir_.join("Scripts", "python37.exe").check()
+    else:
+        assert dir_.join("bin", "python").check()
+        assert dir_.join("bin", "python3").check()
 
 
 def test__resolved_interpreter_none(make_one):