Repository: theacodes/nox (python)

Issue:
Fix conda current environment detection on github actions
On github actions the following command does not output the right environment's package list:

```python
session.run(*["conda", "list"])
```

I am not sure if this is because the command is run from a specific shell (I use `shell: bash -l {0}` in the [workflow definition file](https://github.com/python-qds/qdscreen/blob/7d8e70eab86c6eb324f8dee8680aaf190d32f516/.github/workflows/base.yml#L72)).

I am able to fix this by using explicit environment variables, this is equivalent to the "conda activate <env>" command according to [this source](https://github.com/gqmelo/exec-wrappers/issues/10#issuecomment-237716664) and also [this one](https://stackoverflow.com/a/42660674/7262247):

```python
session.run(*["conda", "list"], env={"CONDA_PREFIX": session.bin, "CONDA_DEFAULT_ENV": session.get_session_id()})
```

The result of both commands (without the fix and with the fix) can be seen on the workflow [here](https://github.com/python-qds/qdscreen/runs/2141057604?check_suite_focus=true#step:10:42). You see that the first displays

```
nox > conda list
 # packages in environment at /usr/share/miniconda/envs/noxenv:
...
```

while the second displays:

```
nox > conda list
 # packages in environment at /home/runner/work/qdscreen/qdscreen/.nox/tests-2-7:
...
```

Note that for some reason on my local computer `session.bin` contains the conda env root folder, while on github actions runner this `session.bin` contains the `<conda_env_root>/bin` subfolder so [I have to remove the "/bin" suffix](https://github.com/python-qds/qdscreen/blob/b2fecb9bf70b2f952f422f61614ef09a9b9abdad/noxfile.py#L84)... any reason why this is so ?

Anyway, this experiment makes me think that maybe it would be a good idea to always add those two environment variables to the `env` when the backend is `conda`, in order to mimic the behaviour of `activate`.

What do you think ?

Pull request description:
Fix current Conda env detection
Closes #406.

Patch:
diff --git a/nox/virtualenv.py b/nox/virtualenv.py
index 02a63e0..19b265d 100644
--- a/nox/virtualenv.py
+++ b/nox/virtualenv.py
@@ -203,7 +203,7 @@ class CondaEnv(ProcessEnv):
         self.reuse_existing = reuse_existing
         self.venv_params = venv_params if venv_params else []
         self.conda_cmd = conda_cmd
-        super().__init__()
+        super().__init__(env={"CONDA_PREFIX": self.location})
 
     def _clean_location(self) -> bool:
         """Deletes existing conda environment"""


Test patch:
diff --git a/tests/test_virtualenv.py b/tests/test_virtualenv.py
index 441eaa8..485e212 100644
--- a/tests/test_virtualenv.py
+++ b/tests/test_virtualenv.py
@@ -13,7 +13,9 @@
 # limitations under the License.
 
 import os
+import re
 import shutil
+import subprocess
 import sys
 from textwrap import dedent
 from unittest import mock
@@ -246,6 +248,24 @@ def test_condaenv_(make_conda):
     assert not venv.is_offline()
 
 
+@pytest.mark.skipif(not HAS_CONDA, reason="Missing conda command.")
+def test_condaenv_detection(make_conda):
+    venv, dir_ = make_conda()
+    venv.create()
+
+    proc_result = subprocess.run(
+        [py.path.local.sysfind("conda").strpath, "list"],
+        env=venv.env,
+        check=True,
+        stdout=subprocess.PIPE,
+        stderr=subprocess.PIPE,
+    )
+    output = proc_result.stdout.decode()
+    path_regex = re.compile(r"packages in environment at (?P<env_dir>.+):")
+
+    assert path_regex.search(output).group("env_dir") == dir_.strpath
+
+
 def test_constructor_defaults(make_one):
     venv, _ = make_one()
     assert venv.location