Bug 1591195 - [lint.shellcheck] Ensure shellcheck subprocess output is returned as text, r=sylvestre

This also adds a test which would have caught the issue.

Differential Revision: https://phabricator.services.mozilla.com/D50621

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

tools/lint/shell/__init__.py

@@ -27,6 +27,7 @@ results = []
 class ShellcheckProcess(ProcessHandlerMixin):
     def __init__(self, config, *args, **kwargs):
         self.config = config
+        kwargs['universal_newlines'] = True
         kwargs['processOutputLine'] = [self.process_line]
         ProcessHandlerMixin.__init__(self, *args, **kwargs)
 

tools/lint/test/files/shellcheck/bad.sh

@@ -0,0 +1,3 @@
+#!/bin/sh
+hello="Hello world"
+echo $1

tools/lint/test/files/shellcheck/good.sh

@@ -0,0 +1,2 @@
+#!/bin/sh
+echo "Hello world"

tools/lint/test/python.ini

@@ -12,3 +12,4 @@ skip-if = os == "win"
 [test_file_whitespace.py]
 [test_file_license.py]
 [test_lintpref.py]
+[test_shellcheck.py]

tools/lint/test/test_shellcheck.py

@@ -0,0 +1,24 @@
+import pytest
+import mozunit
+from mozfile import which
+
+LINTER = 'shellcheck'
+pytestmark = pytest.mark.skipif(not which('shellcheck'), reason="shellcheck is not installed")
+
+
+def test_basic(lint, paths):
+    results = lint(paths())
+    print(results)
+    assert len(results) == 2
+
+    assert "hello appears unused" in results[0].message
+    assert results[0].level == "error"
+    assert results[0].relpath == "bad.sh"
+
+    assert "Double quote to prevent" in results[1].message
+    assert results[1].level == "error"
+    assert results[1].relpath == "bad.sh"
+
+
+if __name__ == '__main__':
+    mozunit.main()