Bug 1473498 - [mach] Pull tests out of make check r=firefox-build-system-reviewers,mshal

Differential Revision: https://phabricator.services.mozilla.com/D36097

--HG--
extra : moz-landing-system : lando

python/mach/mach/test/python.ini

@@ -1,5 +1,6 @@
 [DEFAULT]
 skip-if = python == 3
+subsuite = mach
 
 [test_conditions.py]
 [test_config.py]

taskcluster/ci/source-test/python.yml

@@ -40,6 +40,22 @@ taskgraph-tests:
             - 'taskcluster/**/*.py'
             - 'python/mach/**/*.py'
 
+mach:
+    description: python/mach unit tests
+    platform:
+        - linux64/opt
+        - macosx1010-64/opt
+        - windows10-64/opt
+    python-version: [2]
+    treeherder:
+        symbol: mach
+    run:
+        using: python-test
+        subsuite: mach
+    when:
+        files-changed:
+            - 'python/mach/**'
+
 marionette-harness:
     description: testing/marionette/harness unit tests
     platform: