Unexpected setenv behavior

[pytoxbot]

• Bitbucket: https://bitbucket.org/hpk42/tox/issue/137
• Originally reported by: @cjerdonek
• Originally created at: 2013-11-14T11:20:48.926

The following behavior was unexpected to me. With an ini section like the following:

[testenv]
setenv = FOO = bar
commands = echo {env:FOO}

The environment variable FOO set via setenv is not reflected in the {env:FOO} substitution. I think the documentation should clarify this because it may be surprising to some. Also, there is a typo here (unkown -> unknown).

[pytoxbot]

Original comment by @cjerdonek

I think the trickiest thing will be deciding the rules for what behavior you want. For example, should it be procedurally evaluated (i.e. dependent on the order in which directives are processed), or declarative (i.e. order independent). An example of this is whether it matters if the setenv directives come before or after the substitutions they might affect.

[pytoxbot]

Original comment by @hpk42

You are right. The implementation might not be a few lines of change.

FYI I am actually unhappy about the "up front" expansion on all configs. It should be more lazy. For example, i once had a specific test environment that depended on an environment variable. The environment was not part of envlist, though. I only wanted to execute it sometimes and would be fine if tox gets back to me saying it needs that env variable. As it stands, however, this doesn't work because all environments need to properly expand up-front even if some of them are not actually needed. I haven't really looked into what is needed to make things more lazy. Hopefully it is a change that can be confined to config.py mostly.

[pytoxbot]

Original comment by @cjerdonek

Hmm, this might become subtle then, or not so simple to document. If {env:*} needs to respect setenv, then the behavior could get complicated with things like the following (here is a simple case):

setenv =
  FOO = 1000
  BAR = {env:FOO}

Currently, because {env:*} expands to the values at start-up, there is never any ambiguity.

[pytoxbot]

Original comment by @hpk42

Agreed, this should be fixed, actually. setenv should work for substitutions in commands.

[obestwalter]

As the merged test from @sifuraz shows, this bug has been fixed already.