bluetooth: Add script to generate tests based on templates

third_party/WebKit/LayoutTests/bluetooth/generate.py

+# Copyright 2016 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.
+"""Generator script for Web Bluetooth LayoutTests.
+
+For each script-tests/X.js creates the following test files depending on the
+contents of X.js
+- getPrimaryService/X.html
+- getPrimaryServices/X.html
+- getPrimaryServices/X-with-uuid.html
+
+script-tests/X.js files should contain "CALLS([variation1, variation2,...])"
+tokens that indicate what files to generate. Each variation in CALLS([...])
+should corresponds to a js function call and its arguments. Additionally a
+variation can end in [UUID] to indicate that the generated file's name should
+have the -with-uuid suffix.
+
+For example, for the following template file:
+
+// script-tests/example.js
+promise_test(() => {
+  assert_promise_rejects(navigator.bluetooth.requestDevice(...)
+    .then(device => device.gatt.CALLS(

[Jeffrey Yasskin, 2016/10/19 01:39:23]

You're missing the '[' and ']' in this call, right?

[ortuno, 2016/10/19 04:34:04]

Done.

+      getPrimaryService('heart_rate'),
+      getPrimaryServices('heart_rate')[UUID])));
+}, 'example test');
+
+this script will generate:
+
+// getPrimaryService/example.html
+promise_test(() => {
+  assert_promise_rejects(navigator.bluetooth.requestDevice(...)
+    .then(device => device.gatt.getPrimaryService('heart_rate')));
+}, 'example test');
+
+// getPrimaryServices/example-with-uuid.html
+promise_test(() => {
+  assert_promise_rejects(navigator.bluetooth.requestDevice(...)
+    .then(device => device.gatt.getPrimaryServices('heart_rate')))
+}, 'example test');
+
+Run
+$ python //third_party/WebKit/LayoutTests/bluetooth/generate.py
+and commit the generated files.
+"""
+import glob
+import os
+import re
+import sys
+
+TEMPLATES_DIR = 'script-tests'
+
+
+class GeneratedTest:
+
+  def __init__(self, data, path, template):
+    self.data = data
+    self.path = path
+    self.template = template
+
+
+def GetGeneratedTests():
+  """Yields a GeneratedTest for each call in templates in script-tests."""
+  current_path = os.path.dirname(os.path.realpath(__file__))
+
+  # Read Base Test Template.
+  base_template_file_handle = open(
+      os.path.join(current_path, TEMPLATES_DIR, 'base_test_template.html'))
+  base_template_file_data = base_template_file_handle.read().decode('utf-8')
+  base_template_file_handle.close()
+
+  # Get Templates.
+  available_templates = glob.glob(
+      os.path.join(current_path, TEMPLATES_DIR, '*.js'))
+
+  # Generate Test Files
+  for template in available_templates:
+    # Read template
+    template_file_handle = open(template)
+    template_file_data = template_file_handle.read().decode('utf-8')
+    template_file_handle.close()
+
+    template_name = os.path.splitext(os.path.basename(template))[0]
+
+    result = re.search(r'CALLS\(\[(.*?)\]\)', template_file_data, re.MULTILINE

[Jeffrey Yasskin, 2016/10/19 01:39:23]

If we have a python auto-formatter, then its output is fine, but if not, I'd
rather break the line before re.MULTILINE.

[ortuno, 2016/10/19 04:34:04]

Yeah the auto formatter changed it back to this.

+                       | re.DOTALL)
+
+    if result is None:
+      raise Exception('Template must contain \'CALLS\' tokens')
+
+    new_test_file_data = base_template_file_data.replace('TEST',
+                                                         template_file_data)
+    # Replace CALLS([...]) with CALLS so that we don't have to replace the
+    # CALLS([...]) for every new test file.
+    while result.group() in new_test_file_data:

[Jeffrey Yasskin, 2016/10/19 01:39:24]

I'm confused why this is a loop. Do we expect the same CALLS([...]) content to
appear multiple times?

[ortuno, 2016/10/19 04:34:04]

Yup. Though I realized that it's pretty annoying to have to write CALLS([...])
for every instance. I introduced a new PREVIOUS_CALL token for this.

+      new_test_file_data = new_test_file_data.replace(result.group(), 'CALLS')
+    calls = result.group(1)
+    calls = ''.join(calls.split())

[Jeffrey Yasskin, 2016/10/19 01:39:23]

This removes all the whitespace, right? If so, comment that. It might make more
sense to use a regex for it though.

[ortuno, 2016/10/19 04:34:04]

Added a comment. Apparently this is faster than a regex and also is more
"pythonic"

http://stackoverflow.com/questions/3739909/how-to-strip-all-whitespace-from-s...

+    calls = calls.split(',')
+
+    for call in calls:
+      # Parse call
+      name, args, uuid_suffix = re.search(r'(.*?)\((.*?)\)(\[UUID\])?',
+                                          call).groups()
+
+      # Replace template tokens
+      call_test_file_data = new_test_file_data.replace(
+          'CALLS', '{}({})'.format(name, args))
+      call_test_file_data = call_test_file_data.replace('FUNCTION_NAME', name)

[Jeffrey Yasskin, 2016/10/19 01:39:24]

Please mention this token in the file comment.

[ortuno, 2016/10/19 04:34:04]

Done.

+
+      # Get test file name
+      call_test_file_name = 'gen-{}{}.html'.format(template_name, '-with-uuid'
+                                                   if uuid_suffix else '')
+      call_test_file_path = os.path.join(current_path, name,
+                                         call_test_file_name)
+
+      yield GeneratedTest(call_test_file_data, call_test_file_path, template)
+
+
+def main():

[Jeffrey Yasskin, 2016/10/19 01:39:23]

Could you do a "for f in glob.iglob('gen-*'): os.remove(f)" to make sure excess
files don't stick around?

[ortuno, 2016/10/19 04:34:04]

I'm a bit scared about silently removing files. Do you think it's OK? fwiw: the
presubmit script tests that there are no obsolete gen-* files.

[Jeffrey Yasskin, 2016/10/19 22:33:29]

I *think* it's ok, especially since these files are in version control anyway,
but you're also right to be nervous. We can rely on the presubmit if you prefer.

[ortuno, 2016/10/20 00:27:03]

Acknowledged.

+
+  for generated_test in GetGeneratedTests():
+    # Create or open test file
+    test_file_handle = open(generated_test.path, 'w+')

[Jeffrey Yasskin, 2016/10/19 01:39:24]

Probably use 'wb' for the mode; you don't want \r\n pairs, and you don't need to
read from the file. Any 'w' implies the truncate:
https://docs.python.org/2/library/functions.html#open

[ortuno, 2016/10/19 04:34:04]

Done. Thanks for the link.

+
+    # Write contents
+    test_file_handle.truncate()
+    test_file_handle.write(generated_test.data.encode('utf-8'))
+    test_file_handle.close()
+
+
+if __name__ == '__main__':
+  sys.exit(main())