Respect attempts to change PATH via setenv (tox-dev#1563)

Author: aklajnert

CONTRIBUTORS

@@ -4,6 +4,7 @@ Alexander Schepanovski
 Alexandre Conrad
 Allan Feldman
 Andrii Soldatenko
+Andrzej Klajnert
 Anthon van der Neuth
 Anthony Sottile
 Anudit Nagar

docs/changelog/1423.bugfix.rst

@@ -0,0 +1 @@
+Respect attempts to change `PATH` via `setenv`. - by :user:`aklajnert`

src/tox/venv.py

@@ -557,7 +557,8 @@ def _pcall(
         # construct environment variables
         env.pop("VIRTUALENV_PYTHON", None)
         bin_dir = str(self.envconfig.envbindir)
-        env["PATH"] = os.pathsep.join([bin_dir, os.environ["PATH"]])
+        path = self.envconfig.setenv.get("PATH") or os.environ["PATH"]
+        env["PATH"] = os.pathsep.join([bin_dir, path])
         reporter.verbosity2("setting PATH={}".format(env["PATH"]))
 
         # get command

tests/unit/test_venv.py

@@ -1096,3 +1096,26 @@ def test_create_download(mocksession, newconfig, download):
     else:
         assert "--no-download" in map(str, args)
     mocksession._clearmocks()
+
+
+def test_path_change(tmpdir, mocksession, newconfig, monkeypatch):
+    config = newconfig(
+        [],
+        """\
+        [testenv:python]
+        setenv =
+            PATH = {env:PATH}{:}{toxinidir}/bin
+        """,
+    )
+    pkg = tmpdir.ensure("package.tar.gz")
+    mocksession._clearmocks()
+    mocksession.new_config(config)
+    venv = mocksession.getvenv("python")
+    installpkg(venv, pkg)
+    venv.test()
+
+    pcalls = mocksession._pcalls
+    for x in pcalls:
+        path = x.env["PATH"]
+        assert os.environ["PATH"] in path
+        assert path.endswith(str(venv.envconfig.config.toxinidir) + "/bin")