Add --env option

Suggested by Daniel Silverstone

1 files changed, 16 insertions, 0 deletions

diff --git a/yarn b/yarn
index 2e02eb3..501d10e 100755
--- a/yarn
+++ b/yarn
@@ -64,6 +64,11 @@ class YarnRunner(cliapp.Application):
                 'it should be empty or not exist',
             metavar='DIR')
 
+        self.settings.string_list(
+            ['env'],
+            'add NAME=VALUE to the environment when tests are run',
+            metavar='NAME=VALUE')
+
         self.settings.boolean(
             ['snapshot'],
             'make snapshots of test working directory '
@@ -340,11 +345,22 @@ class YarnRunner(cliapp.Application):
         }
 
         env = {}
+
         for key in whitelisted:
             if key in os.environ:
                 env[key] = os.environ[key]
+
         for key in hardcoded:
             env[key] = hardcoded[key]
+
+        for option_arg in self.settings['env']:
+            if '=' not in option_arg:
+                raise cliapp.AppException(
+                    '--env argument must contain "=" '
+                    'to separate environment variable name and value')
+            key, value = option_arg.split('=', 1)
+            env[key] = value
+
         return env
 
     def run_step(self, datadir, scenario, step, shell_prelude, report_error):