[Files app] Fixes in module conversion script and first unittests

Update the modules generation script with the changes below.

Fix reformatting of single-line dependency lists: empty dependency lists
(e.g. `deps = []`) were rewritten on multiple lines (deps = [\n])
incorrectly.

In the `find_dependencies` function, simplify calls to
`add_dependency` by the need for redundant `if is_unittest... else...`.

"//chrome/test/data/webui:chai_assert" can be imported in non-unittest
files, and "//ui/webui/resources/js" can be imported in unittest files.
Remove unittest distinction when importing variabble from these
locations.

Fix function exports: The detection of functions used a variable
(the name of the function the export) that was not defined.

Fix test function exports: when converting the same unittest multiple
times, the "export" keyword was added multiple times in front of each
test function to be exported.

Facilitate testing by adding a `add_js_file_exports` function that
takes `file_lines` as arguments (`convert_js_file` is harder to test
directly, taking a file path as argument).

Fix edge case where, when the only reported closure error is about
extending `EventTarget`, the script doesn't do what's needed to fix it:
Run `find_dependencies` whether or not there is any variable to import.

Add unittests and presubmit script.

Bug: 1133186
Test: ui/file_manager/base/tools/modules_test.py
Change-Id: Ia0ed675576d021b3b952215384e7a491ff7f4430
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2580970
Commit-Queue: Jeremie Boulic <jboulic@chromium.org>
Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Cr-Commit-Position: refs/heads/master@{#836525}

ui/file_manager/base/tools/PRESUBMIT.py

+# Copyright 2020 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+"""Presubmit script for files in ui/file_manager/base/tools/
+
+See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
+for more details about the presubmit API built into depot_tools.
+"""
+
+
+def RunTests(input_api, output_api):
+    presubmit_path = input_api.PresubmitLocalPath()
+    sources = ['modules_test.py']
+    tests = [input_api.os_path.join(presubmit_path, s) for s in sources]
+    return input_api.canned_checks.RunUnitTests(input_api, output_api, tests)
+
+
+def _CheckChangeOnUploadOrCommit(input_api, output_api):
+    results = []
+    affected = input_api.AffectedFiles()
+
+    def is_in_current_folder(f):
+      dirname = input_api.os_path.dirname(f.LocalPath())
+      return dirname == u'ui/file_manager/base/tools'
+
+    # Check if any of the modified files is in 'ui/file_manager/base/tools'.
+    if any([is_in_current_folder(f) for f in affected]):
+        results += RunTests(input_api, output_api)
+
+    return results
+
+
+def CheckChangeOnUpload(input_api, output_api):
+    return _CheckChangeOnUploadOrCommit(input_api, output_api)
+
+
+def CheckChangeOnCommit(input_api, output_api):
+    return _CheckChangeOnUploadOrCommit(input_api, output_api)

ui/file_manager/base/tools/modules_test.py

+#!/usr/bin/env python
+# Copyright 2020 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import unittest
+import modules
+import os
+
+_HERE_DIR = os.path.dirname(__file__)
+
+
+class ModulesConversionTest(unittest.TestCase):
+    def _get_file_lines(self, file):
+        path = os.path.join(_HERE_DIR, 'tests', file)
+        return modules.get_file_lines(path)
+
+    def _debug_file_contents(self, file_lines, expected_file_lines):
+        print '\n------- FILE -------'
+        print '\n'.join(file_lines)
+        print '----- EXPECTED -----'
+        print '\n'.join(expected_file_lines)
+        print '--------------------\n'
+
+    def testExportFunction(self):
+        '''Tests exporting functions that are not used locally.'''
+        file_lines = self._get_file_lines('export_function.js')
+        expected_file_lines = self._get_file_lines(
+            'export_function_expected.js')
+
+        # Check: function is exported correctly.
+        modules.add_js_file_exports(file_lines)
+        self.assertEquals(file_lines, expected_file_lines)
+
+        # Check: running add_js_file_exports a second time produces the same
+        # expected output.
+        modules.add_js_file_exports(file_lines)
+        self.assertEquals(file_lines, expected_file_lines)
+
+    def testExportLocalFunction(self):
+        '''Tests that functions that are used locally are not be exported.'''
+        file_lines = self._get_file_lines('export_local_function.js')
+        expected_file_lines = self._get_file_lines(
+            'export_local_function_expected.js')
+
+        # Check: local function is not exported.
+        modules.add_js_file_exports(file_lines)
+        self.assertEquals(file_lines, expected_file_lines)
+
+    def testUpdateEmptyDependencyList(self):
+        '''Tests adding a dependency to an empty dependency list.'''
+        file_lines = self._get_file_lines('empty_dependency_list.gn')
+        expected_file_lines = self._get_file_lines(
+            'empty_dependency_list_expected.gn')
+        rule_first_line = 'js_unittest("importer_common_unittest.m") {'
+        list_name = 'deps'
+        dependency_line = '    "//ui/file_manager/base/js:mock_chrome",'
+
+        # Check: dependency list correctly updated with new dependency.
+        modules.add_dependency(file_lines, rule_first_line, list_name,
+                               dependency_line)
+        self.assertEquals(file_lines, expected_file_lines)
+
+        # Check: running add_dependency a second time produces the same
+        # expected output (no duplicate dependency).
+        modules.add_dependency(file_lines, rule_first_line, list_name,
+                               dependency_line)
+        self.assertEquals(file_lines, expected_file_lines)
+
+    def testUpdateSingleLineDependencyList(self):
+        '''Tests adding a dependency to an single-line dependency list.'''
+        file_lines = self._get_file_lines('single_line_dependency_list.gn')
+        expected_file_lines = self._get_file_lines(
+            'single_line_dependency_list_expected.gn')
+        rule_first_line = 'js_unittest("importer_common_unittest.m") {'
+        list_name = 'deps'
+        dependency_line = '    "//ui/file_manager/base/js:mock_chrome",'
+
+        # Check: dependency list correctly formatted and updated with new
+        # dependency.
+        modules.add_dependency(file_lines, rule_first_line, list_name,
+                               dependency_line)
+        self.assertEquals(file_lines, expected_file_lines)
+
+
+if __name__ == '__main__':
+    unittest.main()

ui/file_manager/base/tools/tests/empty_dependency_list.gn

+
+js_unittest("importer_common_unittest.m") {
+  deps = []
+}

ui/file_manager/base/tools/tests/empty_dependency_list_expected.gn

+
+js_unittest("importer_common_unittest.m") {
+  deps = [
+    "//ui/file_manager/base/js:mock_chrome",
+  ]
+}

ui/file_manager/base/tools/tests/export_function.js

+
+function Foo() {}
+Foo.types = [];

ui/file_manager/base/tools/tests/export_function_expected.js

+
+/* #export */ function Foo() {}
+Foo.types = [];

ui/file_manager/base/tools/tests/export_local_function.js

+
+function Foo() {}
+Foo();

ui/file_manager/base/tools/tests/export_local_function_expected.js

+
+function Foo() {}
+Foo();

ui/file_manager/base/tools/tests/single_line_dependency_list.gn

+
+js_unittest("importer_common_unittest.m") {
+  deps = [ ":mock_entry" ]
+}

ui/file_manager/base/tools/tests/single_line_dependency_list_expected.gn

+
+js_unittest("importer_common_unittest.m") {
+  deps = [
+    "//ui/file_manager/base/js:mock_chrome",
+    ":mock_entry",
+  ]
+}