Make optional env replacements use the ``env`` keyword

The ':' character is a reserved character in shell, meaning it cannot
be used as part of the ENV variable name. If the ENV key has a ':'
in it split on the ':' and use the second value as the default
instead of raising an exception.

3 files changed, 16 insertions, 23 deletions

diff --git a/doc/config.txt b/doc/config.txt
index 5a9134d..c53df68 100644
--- a/doc/config.txt
+++ b/doc/config.txt
@@ -298,7 +298,7 @@ environment variable substitutions with default values
 
 If you specify a substitution string like this::
 
-    {defenv:DEFAULTVALUE:KEY}
+    {env:KEY:DEFAULTVALUE}
 
 then the value will be retrieved as ``os.environ['KEY']``
 and replace with DEFAULTVALUE if the environment variable does not
@@ -306,7 +306,7 @@ exist.
 
 If you specify a substitution string like this::
 
-    {defenv::KEY}
+    {env:KEY:}
 
 then the value will be retrieved as ``os.environ['KEY']``
 and replace with and empty string if the environment variable does not
diff --git a/tests/test_config.py b/tests/test_config.py
index 3084001..3647673 100644
--- a/tests/test_config.py
+++ b/tests/test_config.py
@@ -246,9 +246,9 @@ class TestIniParser:
         monkeypatch.setenv("KEY1", "hello")
         config = newconfig("""
             [section]
-            key1={defenv:DEFAULT_VALUE:KEY1}
-            key2={defenv:DEFAULT_VALUE:KEY2}
-            key3={defenv::KEY3}
+            key1={env:KEY1:DEFAULT_VALUE}
+            key2={env:KEY2:DEFAULT_VALUE}
+            key3={env:KEY3:}
         """)
         reader = IniReader(config._cfg)
         x = reader.getdefault("section", "key1")
diff --git a/tox/_config.py b/tox/_config.py
index 468af5f..86ab3a0 100644
--- a/tox/_config.py
+++ b/tox/_config.py
@@ -595,11 +595,20 @@ class IniReader:
         #print "getdefault", section, name, "returned", repr(x)
         return x
 
-    def _do_replace_env(self, envkey, default=None):
-        if not envkey:
+    def _replace_env(self, match):
+        match_value = match.group('substitution_value')
+        if not match_value:
             raise tox.exception.ConfigError(
                 'env: requires an environment variable name')
 
+        default = None
+        envkey_split = match_value.split(':', 1)
+
+        if len(envkey_split) is 2:
+            envkey, default = envkey_split
+        else:
+            envkey = match_value
+
         if not envkey in os.environ and default is None:
             raise tox.exception.ConfigError(
                 "substitution env:%r: unkown environment variable %r" %
@@ -607,21 +616,6 @@ class IniReader:
 
         return os.environ.get(envkey, default)
 
-    def _replace_env(self, match):
-        envkey = match.group('substitution_value')
-        return self._do_replace_env(envkey)
-
-    def _replace_env_with_default(self, match):
-        envkey = match.group('substitution_value')
-        try:
-            default, envkey = envkey.split(':', 1)
-        except ValueError:
-            raise tox.exception.ConfigError(
-                "substitution 'defenv:%r': malformed, expected "
-                "'defenv:DEFAULTVALUE:KEY'" % match)
-
-        return self._do_replace_env(envkey, default=default)
-
     def _substitute_from_other_section(self, key):
         if key.startswith("[") and "]" in key:
             i = key.find("]")
@@ -661,7 +655,6 @@ class IniReader:
 
         handlers = {
             'env' : self._replace_env,
-            'defenv' : self._replace_env_with_default,
             None : self._replace_substitution,
             }
         try: