Bug 1460690 - [mozlint] Make sure vcs_paths are always joined to the repository root, r=standard8

Files returned from version control (i.e via --outgoing or --workdir), are currently joined to
cwd. This will cause failures if |mach lint| is run from anywhere other than topsrcdir.

However we *do* want to join manually specified paths to cwd so things like:
cd devtools && mach lint client

continue to work. This patch makes sure we join the proper kind of path to the proper place.

MozReview-Commit-ID: EQmRhAr3Oog

--HG--
extra : rebase_source : 2629cc27f79059e44369d46d4f8278f83923582c

python/mozlint/mozlint/roller.py

@@ -156,8 +156,7 @@ class LintRoller(object):
             else:
                 lpaths = paths.union(vcs_paths)
 
-            lpaths = lpaths or ['.']
-            lpaths = map(os.path.abspath, lpaths)
+            lpaths = list(lpaths) or [os.getcwd()]
             chunk_size = min(self.MAX_PATHS_PER_JOB, int(ceil(len(lpaths) / num_procs))) or 1
             assert chunk_size > 0
 
@@ -223,6 +222,11 @@ class LintRoller(object):
             print("warning: no files linted")
             return {}
 
+        # Make sure all paths are absolute. Join `paths` to cwd and `vcs_paths` to root.
+        paths = set(map(os.path.abspath, paths))
+        vcs_paths = set([os.path.join(self.root, p) if not os.path.isabs(p) else p
+                         for p in vcs_paths])
+
         num_procs = num_procs or cpu_count()
         jobs = list(self._generate_jobs(paths, vcs_paths, num_procs))
 

python/mozlint/test/test_roller.py

@@ -50,6 +50,36 @@ def test_roll_successful(lint, linters, files):
     assert container.rule == 'no-foobar'
 
 
+def test_roll_from_subdir(lint, linters):
+    lint.read(linters)
+
+    oldcwd = os.getcwd()
+    try:
+        os.chdir(os.path.join(lint.root, 'files'))
+
+        # Path relative to cwd works
+        result = lint.roll('no_foobar.js')
+        assert len(result) == 0
+        assert len(lint.failed) == 0
+
+        # Path relative to root doesn't work
+        result = lint.roll(os.path.join('files', 'no_foobar.js'))
+        assert len(result) == 0
+        assert len(lint.failed) == 3
+
+        # Paths from vcs are always joined to root instead of cwd
+        lint.mock_vcs([os.path.join('files', 'no_foobar.js')])
+        result = lint.roll(outgoing=True)
+        assert len(result) == 0
+        assert len(lint.failed) == 0
+
+        result = lint.roll(workdir=True)
+        assert len(result) == 0
+        assert len(lint.failed) == 0
+    finally:
+        os.chdir(oldcwd)
+
+
 def test_roll_catch_exception(lint, lintdir, files, capfd):
     lint.read(os.path.join(lintdir, 'raises.yml'))