Un-escape backslashes before populating os.environ

Related to #1656

Author: jayvdb

docs/changelog/1690.bugfix.rst

@@ -0,0 +1,2 @@
+Fixed regression in v3.20.0 that caused escaped curly braces in setenv
+to break usage of the variable elsewhere in tox.ini. - by :user:`jayvdb`

src/tox/config/__init__.py

@@ -408,6 +408,19 @@ def __setitem__(self, name, value):
         self.definitions[name] = value
         self.resolved[name] = value
 
+    def items(self):
+        return ((name, self[name]) for name in self.definitions)
+
+    def export(self):
+        # post-process items to avoid internal syntax/semantics
+        # such as {} being escaped using \{\}, suitable for use with
+        # os.environ .
+        return {
+            name: Replacer._unescape(value)
+            for name, value in self.items()
+            if value is not self._DUMMY
+        }
+
 
 @tox.hookimpl
 def tox_addoption(parser):
@@ -1785,6 +1798,10 @@ def substitute_once(x):
 
         return expanded
 
+    @staticmethod
+    def _unescape(s):
+        return s.replace("\\{", "{").replace("\\}", "}")
+
     def _replace_match(self, match):
         g = match.groupdict()
         sub_value = g["substitution_value"]
@@ -1924,7 +1941,7 @@ def processcommand(cls, reader, command, replace=True):
                 new_arg = ""
                 new_word = reader._replace(word)
                 new_word = reader._replace(new_word)
-                new_word = new_word.replace("\\{", "{").replace("\\}", "}")
+                new_word = Replacer._unescape(new_word)
                 new_arg += new_word
                 newcommand += new_arg
         else:

src/tox/venv.py

@@ -493,7 +493,7 @@ def _get_os_environ(self, is_test_command=False):
             env = os.environ.copy()
 
         # in any case we honor per-testenv setenv configuration
-        env.update(self.envconfig.setenv)
+        env.update(self.envconfig.setenv.export())
 
         env["VIRTUAL_ENV"] = str(self.path)
         return env

tests/unit/config/test_config.py

@@ -2734,13 +2734,22 @@ def test_setenv_env_file(self, newconfig, content, has_magic, tmp_path):
                 env_path,
             ),
         ).envconfigs["python"]
+
         envs = env_config.setenv.definitions
+
         assert envs["ALPHA"] == "1"
         if has_magic:
             assert envs["MAGIC"] == "yes"
         else:
             assert "MAGIC" not in envs
 
+        expected_vars = ["ALPHA", "PYTHONHASHSEED", "TOX_ENV_DIR", "TOX_ENV_NAME"]
+        if has_magic:
+            expected_vars = sorted(expected_vars + ["MAGIC"])
+
+        exported = env_config.setenv.export()
+        assert sorted(exported) == expected_vars
+
 
 class TestIndexServer:
     def test_indexserver(self, newconfig):

tests/unit/test_venv.py

@@ -3,6 +3,7 @@
 
 import py
 import pytest
+from six import PY2
 
 import tox
 from tox.interpreters import NoInterpreterInfo
@@ -770,21 +771,36 @@ def test_pythonpath_empty(self, newmocksession, monkeypatch, caplog):
         assert "PYTHONPATH" not in pcalls[0].env
 
 
-def test_env_variables_added_to_pcall(tmpdir, mocksession, newconfig, monkeypatch):
+def test_env_variables_added_to_pcall(tmpdir, mocksession, newconfig, monkeypatch, tmp_path):
     monkeypatch.delenv("PYTHONPATH", raising=False)
     pkg = tmpdir.ensure("package.tar.gz")
     monkeypatch.setenv("X123", "123")
     monkeypatch.setenv("YY", "456")
+    env_path = tmp_path / ".env"
+    env_file_content = "ENV_FILE_VAR = file_value"
+    env_path.write_text(env_file_content.decode() if PY2 else env_file_content)
+
     config = newconfig(
         [],
-        """\
+        r"""
+        [base]
+        base_var = base_value
+
         [testenv:python]
         commands=python -V
         passenv = x123
         setenv =
             ENV_VAR = value
+            ESCAPED_VAR = \{value\}
+            ESCAPED_VAR2 = \\{value\\}
+            BASE_VAR = {[base]base_var}
             PYTHONPATH = value
-        """,
+            TTY_VAR = {tty:ON_VALUE:OFF_VALUE}
+            COLON = {:}
+            REUSED_FILE_VAR = reused {env:ENV_FILE_VAR}
+            file| %s
+        """
+        % env_path,
     )
     mocksession._clearmocks()
     mocksession.new_config(config)
@@ -799,10 +815,18 @@ def test_env_variables_added_to_pcall(tmpdir, mocksession, newconfig, monkeypatc
         assert env is not None
         assert "ENV_VAR" in env
         assert env["ENV_VAR"] == "value"
+        assert env["ESCAPED_VAR"] == "{value}"
+        assert env["ESCAPED_VAR2"] == r"\{value\}"
+        assert env["COLON"] == ";" if sys.platform == "win32" else ":"
+        assert env["TTY_VAR"] == "OFF_VALUE"
+        assert env["ENV_FILE_VAR"] == "file_value"
+        assert env["REUSED_FILE_VAR"] == "reused file_value"
+        assert env["BASE_VAR"] == "base_value"
         assert env["VIRTUAL_ENV"] == str(venv.path)
         assert env["X123"] == "123"
         assert "PYTHONPATH" in env
         assert env["PYTHONPATH"] == "value"
+
     # all env variables are passed for installation
     assert pcalls[0].env["YY"] == "456"
     assert "YY" not in pcalls[1].env