Reorganize Servo's WPT Python scripts

This change moves all of Servo's WPT Python support scripts into one
directory as they were previously scattered throughout the directory
structure. This should allow more code reuse and make it easier to
understand how everything fits together.

The changes:

- `tests/wpt/update` → `python/wpt/importer`
- `etc/ci/upstream-wpt-changes/wptupstreamer` → `python/wpt/exporter`
- `etc/ci/upstream-wpt-changes/test.py` → `python/wpt/test.py`
- `etc/ci/upstream-wpt-changes/tests` → `python/wpt/tests`
- `tests/wpt/servowpt.py` →
    - `python/wpt/update.py`
    - `python/wpt/run.py`
- `tests/wpt/manifestupdate.py` → `python/wpt/manifestupdate.py`

This change also removes
 - The ability to run the `update-wpt` and `test-wpt` commands without
   using `mach`. These didn't work very well, because it was difficult
   to get all of the wptrunner and mach dependencies installed outside
   of the Python virtualenv. It's simpler if they are always run through
   `mach`.
- The old WPT change upstreaming script that was no longer used.

python/wpt/grouping_formatter.py

@@ -0,0 +1,367 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+# This allows using types that are defined later in the file.
+from __future__ import annotations
+
+import collections
+import os
+import sys
+import mozlog
+import mozlog.formatters.base
+import mozlog.reader
+
+from dataclasses import dataclass, field
+from typing import Dict, List, Optional, Any
+from six import itervalues
+
+DEFAULT_MOVE_UP_CODE = u"\x1b[A"
+DEFAULT_CLEAR_EOL_CODE = u"\x1b[K"
+
+
+@dataclass
+class UnexpectedSubtestResult():
+    path: str
+    subtest: str
+    actual: str
+    expected: str
+    message: str
+    time: int
+    stack: Optional[str]
+
+
+@dataclass
+class UnexpectedResult():
+    path: str
+    actual: str
+    expected: str
+    message: str
+    time: int
+    stack: Optional[str]
+    unexpected_subtest_results: list[UnexpectedSubtestResult] = field(
+        default_factory=list)
+    issues: list[str] = field(default_factory=list)
+    flaky: bool = False
+
+    def __str__(self):
+        output = UnexpectedResult.to_lines(self)
+
+        if self.unexpected_subtest_results:
+            def make_subtests_failure(subtest_results):
+                # Test names sometimes contain control characters, which we want
+                # to be printed in their raw form, and not their interpreted form.
+                lines = []
+                for subtest in subtest_results[:-1]:
+                    lines += UnexpectedResult.to_lines(
+                        subtest, print_stack=False)
+                lines += UnexpectedResult.to_lines(subtest_results[-1])
+                return self.wrap_and_indent_lines(lines, "  ").splitlines()
+
+            # Organize the failures by stack trace so we don't print the same stack trace
+            # more than once. They are really tall and we don't want to flood the screen
+            # with duplicate information.
+            results_by_stack = collections.defaultdict(list)
+            for subtest_result in self.unexpected_subtest_results:
+                results_by_stack[subtest_result.stack].append(subtest_result)
+
+            # Print stackless results first. They are all separate.
+            if None in results_by_stack:
+                output += make_subtests_failure(results_by_stack.pop(None))
+            for subtest_results in results_by_stack.values():
+                output += make_subtests_failure(subtest_results)
+
+        return UnexpectedResult.wrap_and_indent_lines(output, "  ")
+
+    @staticmethod
+    def wrap_and_indent_lines(lines, indent):
+        if not lines:
+            return ""
+
+        output = indent + u"\u25B6 %s\n" % lines[0]
+        for line in lines[1:-1]:
+            output += indent + u"\u2502 %s\n" % line
+        if len(lines) > 1:
+            output += indent + u"\u2514 %s\n" % lines[-1]
+        return output
+
+    @staticmethod
+    def to_lines(result: Any[UnexpectedSubtestResult, UnexpectedResult], print_stack=True):
+        first_line = result.actual
+        if result.expected != result.actual:
+            first_line += f" [expected {result.expected}]"
+
+        # Test names sometimes contain control characters, which we want
+        # to be printed in their raw form, and not their interpreted form.
+        first_line += f" {result.path.encode('unicode-escape').decode('utf-8')}"
+
+        if isinstance(result, UnexpectedResult) and result.issues:
+            first_line += f" ({', '.join([f'#{bug}' for bug in result.issues])})"
+
+        lines = [first_line]
+        if result.message:
+            for message_line in result.message.splitlines():
+                lines.append(f"  \u2192 {message_line}")
+        if print_stack and result.stack:
+            lines.append("")
+            lines.extend(result.stack.splitlines())
+        return lines
+
+
+class ServoHandler(mozlog.reader.LogHandler):
+    """LogHandler designed to collect unexpected results for use by
+       script or by the ServoFormatter output formatter."""
+    def __init__(self):
+        self.reset_state()
+
+    def reset_state(self):
+        self.number_of_tests = 0
+        self.completed_tests = 0
+        self.need_to_erase_last_line = False
+        self.running_tests: Dict[str, str] = {}
+        self.test_output = collections.defaultdict(str)
+        self.subtest_failures = collections.defaultdict(list)
+        self.tests_with_failing_subtests = []
+        self.unexpected_results: List[UnexpectedResult] = []
+
+        self.expected = {
+            'OK': 0,
+            'PASS': 0,
+            'FAIL': 0,
+            'ERROR': 0,
+            'TIMEOUT': 0,
+            'SKIP': 0,
+            'CRASH': 0,
+            'PRECONDITION_FAILED': 0,
+        }
+
+        self.unexpected_tests = {
+            'OK': [],
+            'PASS': [],
+            'FAIL': [],
+            'ERROR': [],
+            'TIMEOUT': [],
+            'CRASH': [],
+            'PRECONDITION_FAILED': [],
+        }
+
+    def suite_start(self, data):
+        self.reset_state()
+        self.number_of_tests = sum(len(tests) for tests in itervalues(data["tests"]))
+        self.suite_start_time = data["time"]
+
+    def suite_end(self, _):
+        pass
+
+    def test_start(self, data):
+        self.running_tests[data['thread']] = data['test']
+
+    @staticmethod
+    def data_was_for_expected_result(data):
+        if "expected" not in data:
+            return True
+        return "known_intermittent" in data \
+            and data["status"] in data["known_intermittent"]
+
+    def test_end(self, data: dict) -> Optional[UnexpectedResult]:
+        self.completed_tests += 1
+        test_status = data["status"]
+        test_path = data["test"]
+        del self.running_tests[data['thread']]
+
+        had_expected_test_result = self.data_was_for_expected_result(data)
+        subtest_failures = self.subtest_failures.pop(test_path, [])
+        if had_expected_test_result and not subtest_failures:
+            self.expected[test_status] += 1
+            return None
+
+        # If the test crashed or timed out, we also include any process output,
+        # because there is a good chance that the test produced a stack trace
+        # or other error messages.
+        stack = data.get("stack", None)
+        if test_status in ("CRASH", "TIMEOUT"):
+            stack = f"\n{stack}" if stack else ""
+            stack = f"{self.test_output[test_path]}{stack}"
+
+        result = UnexpectedResult(
+            test_path,
+            test_status,
+            data.get("expected", test_status),
+            data.get("message", ""),
+            data["time"],
+            stack,
+            subtest_failures
+        )
+
+        if not had_expected_test_result:
+            self.unexpected_tests[result.actual].append(data)
+        if subtest_failures:
+            self.tests_with_failing_subtests.append(data)
+
+        self.unexpected_results.append(result)
+        return result
+
+    def test_status(self, data: dict):
+        if self.data_was_for_expected_result(data):
+            return
+        self.subtest_failures[data["test"]].append(UnexpectedSubtestResult(
+            data["test"],
+            data["subtest"],
+            data["status"],
+            data["expected"],
+            data.get("message", ""),
+            data["time"],
+            data.get('stack', None),
+        ))
+
+    def process_output(self, data):
+        if data['thread'] not in self.running_tests:
+            return
+        test_name = self.running_tests[data['thread']]
+        self.test_output[test_name] += data['data'] + "\n"
+
+    def log(self, _):
+        pass
+
+
+class ServoFormatter(mozlog.formatters.base.BaseFormatter, ServoHandler):
+    """Formatter designed to produce unexpected test results grouped
+       together in a readable format."""
+    def __init__(self):
+        ServoHandler.__init__(self)
+        self.current_display = ""
+        self.interactive = os.isatty(sys.stdout.fileno())
+
+        if self.interactive:
+            self.line_width = os.get_terminal_size().columns
+            self.move_up = DEFAULT_MOVE_UP_CODE
+            self.clear_eol = DEFAULT_CLEAR_EOL_CODE
+
+            try:
+                import blessings
+                self.terminal = blessings.Terminal()
+                self.move_up = self.terminal.move_up
+                self.clear_eol = self.terminal.clear_eol
+            except Exception as exception:
+                sys.stderr.write("GroupingFormatter: Could not get terminal "
+                                 "control characters: %s\n" % exception)
+
+    def text_to_erase_display(self):
+        if not self.interactive or not self.current_display:
+            return ""
+        return ((self.move_up + self.clear_eol)
+                * self.current_display.count('\n'))
+
+    def generate_output(self, text=None, new_display=None):
+        if not self.interactive:
+            return text
+
+        output = self.text_to_erase_display()
+        if text:
+            output += text
+        if new_display is not None:
+            self.current_display = new_display
+        return output + self.current_display
+
+    def test_counter(self):
+        if self.number_of_tests == 0:
+            return "  [%i] " % self.completed_tests
+        else:
+            return "  [%i/%i] " % (self.completed_tests, self.number_of_tests)
+
+    def build_status_line(self):
+        new_display = self.test_counter()
+
+        if self.running_tests:
+            indent = " " * len(new_display)
+            if self.interactive:
+                max_width = self.line_width - len(new_display)
+            else:
+                max_width = sys.maxsize
+            return new_display + ("\n%s" % indent).join(
+                val[:max_width] for val in self.running_tests.values()) + "\n"
+        else:
+            return new_display + "No tests running.\n"
+
+    def suite_start(self, data):
+        ServoHandler.suite_start(self, data)
+        if self.number_of_tests == 0:
+            return "Running tests in %s\n\n" % data[u'source']
+        else:
+            return "Running %i tests in %s\n\n" % (self.number_of_tests, data[u'source'])
+
+    def test_start(self, data):
+        ServoHandler.test_start(self, data)
+        if self.interactive:
+            return self.generate_output(new_display=self.build_status_line())
+
+    def test_end(self, data):
+        unexpected_result = ServoHandler.test_end(self, data)
+        if not unexpected_result:
+            if self.interactive:
+                return self.generate_output(new_display=self.build_status_line())
+            else:
+                return self.generate_output(text="%s%s\n" % (self.test_counter(), data["test"]))
+
+        # Surround test output by newlines so that it is easier to read.
+        output_for_unexpected_test = f"{unexpected_result}\n"
+        return self.generate_output(text=output_for_unexpected_test,
+                                    new_display=self.build_status_line())
+
+    def test_status(self, data):
+        ServoHandler.test_status(self, data)
+
+    def suite_end(self, data):
+        ServoHandler.suite_end(self, data)
+        if not self.interactive:
+            output = u"\n"
+        else:
+            output = ""
+
+        output += u"Ran %i tests finished in %.1f seconds.\n" % (
+            self.completed_tests, (data["time"] - self.suite_start_time) / 1000)
+        output += u"  \u2022 %i ran as expected. %i tests skipped.\n" % (
+            sum(self.expected.values()), self.expected['SKIP'])
+
+        def text_for_unexpected_list(text, section):
+            tests = self.unexpected_tests[section]
+            if not tests:
+                return u""
+            return u"  \u2022 %i tests %s\n" % (len(tests), text)
+
+        output += text_for_unexpected_list(u"crashed unexpectedly", 'CRASH')
+        output += text_for_unexpected_list(u"had errors unexpectedly", 'ERROR')
+        output += text_for_unexpected_list(u"failed unexpectedly", 'FAIL')
+        output += text_for_unexpected_list(u"precondition failed unexpectedly", 'PRECONDITION_FAILED')
+        output += text_for_unexpected_list(u"timed out unexpectedly", 'TIMEOUT')
+        output += text_for_unexpected_list(u"passed unexpectedly", 'PASS')
+        output += text_for_unexpected_list(u"unexpectedly okay", 'OK')
+
+        num_with_failing_subtests = len(self.tests_with_failing_subtests)
+        if num_with_failing_subtests:
+            output += (u"  \u2022 %i tests had unexpected subtest results\n"
+                       % num_with_failing_subtests)
+        output += "\n"
+
+        # Repeat failing test output, so that it is easier to find, since the
+        # non-interactive version prints all the test names.
+        if not self.interactive and self.unexpected_results:
+            output += u"Tests with unexpected results:\n"
+            output += "".join([str(result)
+                              for result in self.unexpected_results])
+
+        return self.generate_output(text=output, new_display="")
+
+    def process_output(self, data):
+        ServoHandler.process_output(self, data)
+
+    def log(self, data):
+        ServoHandler.log(self, data)
+
+        # We are logging messages that begin with STDERR, because that is how exceptions
+        # in this formatter are indicated.
+        if data['message'].startswith('STDERR'):
+            return self.generate_output(text=data['message'] + "\n")
+
+        if data['level'] in ('CRITICAL', 'ERROR'):
+            return self.generate_output(text=data['message'] + "\n")