If the {env:key:default} paremeter is found in the config but there are no environment variables yet, fall back to the current section setenv variables

1 files changed, 15 insertions, 4 deletions

diff --git a/tox/config.py b/tox/config.py
index d68d276..17fdccf 100644
--- a/tox/config.py
+++ b/tox/config.py
@@ -903,6 +903,7 @@ class SectionReader:
         return '\n'.join(filter(None, map(factor_line, lines)))
 
     def _replace_env(self, match):
+        env_list = self._build_envs_list()
         match_value = match.group('substitution_value')
         if not match_value:
             raise tox.exception.ConfigError(
@@ -917,11 +918,21 @@ class SectionReader:
             envkey = match_value
 
         if envkey not in os.environ and default is None:
-            raise tox.exception.ConfigError(
-                "substitution env:%r: unknown environment variable %r" %
-                (envkey, envkey))
+            if envkey not in env_list and default is None:
+                raise tox.exception.ConfigError(
+                    "substitution env:%r: unknown environment variable %r" %
+                    (envkey, envkey))
+        if envkey in os.environ:
+            return os.environ.get(envkey, default)
+        else:
+            return env_list.get(envkey, default)
 
-        return os.environ.get(envkey, default)
+    def _build_envs_list(self):
+        full_envs = self._cfg[self.section_name].get('setenv')
+        if full_envs:
+            return {k.split('=')[0]: k.split('=')[1] for k in full_envs.split('\n')}
+        else:
+            return {}
 
     def _substitute_from_other_section(self, key):
         if key.startswith("[") and "]" in key: