Take Ownership of the Incremental Parse Utility

Technically we aren't using this, but we haven't decided what
to do about the old incremental parsing tests. For now, move
these tools into its last consumer - swift-syntax - to unblock
the build.

Author: CodaFi

build-script.py

@@ -35,7 +35,7 @@
 SWIFT_DIR = os.path.join(WORKSPACE_DIR, "swift")
 
 INCR_TRANSFER_ROUNDTRIP_EXEC = os.path.join(
-    SWIFT_DIR, "utils", "incrparse", "incr_transfer_round_trip.py"
+    PACKAGE_DIR, "utils", "incrparse", "incr_transfer_round_trip.py"
 )
 
 GYB_EXEC = os.path.join(SWIFT_DIR, "utils", "gyb")

utils/incrparse/incr_transfer_round_trip.py

@@ -0,0 +1,118 @@
+#!/usr/bin/env python3
+
+import argparse
+import os
+import subprocess
+import sys
+
+from test_util import TestFailedError, prepareForIncrParse, run_command
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+        description='Utility for testing incremental syntax parsing',
+        epilog='''
+    Based of a single template the utility generates a pre-edit and a post-edit
+    file. It then verifies that incrementally parsing the post-edit file base
+    on the pre-edit file results in the same syntax tree as reparsing the
+    post-edit file from scratch.
+
+    To generate the pre-edit and the post-edit file from the template, it
+    operates on markers of the form:
+
+        <<test_case<pre|||post>>>
+
+    These placeholders are replaced by:
+      - 'pre' if a different test case than 'test_case' is run
+      - 'pre' for the pre-edit version of 'test_case'
+      - 'post' for the post-edit version of 'test_case'
+    ''')
+    parser.add_argument(
+        'file', type=argparse.FileType(),
+        help='The template file to test')
+    parser.add_argument(
+        '--test-case', default='',
+        help='The test case to execute. If no test case is specified all \
+              unnamed substitutions are applied')
+    parser.add_argument(
+        '--temp-dir', required=True,
+        help='A temporary directory where pre-edit and post-edit files can be \
+              saved')
+    parser.add_argument(
+        '--swiftsyntax-lit-test-helper', required=True,
+        help='The path to the lit-test-helper binary of SwiftSyntax')
+
+    args = parser.parse_args(sys.argv[1:])
+
+    test_file = args.file.name
+    test_file_name = os.path.basename(test_file)
+    test_case = args.test_case
+    temp_dir = args.temp_dir
+    swiftsyntax_lit_test_helper = args.swiftsyntax_lit_test_helper
+
+    if not os.path.exists(temp_dir):
+        os.makedirs(temp_dir)
+
+    pre_edit_file = temp_dir + '/' + test_file_name + '.' + test_case + \
+        '.pre.swift'
+    post_edit_file = temp_dir + '/' + test_file_name + '.' + test_case + \
+        '.post.swift'
+    after_roundtrip_file = temp_dir + '/' + test_file_name + '.' \
+        + test_case + '.post_after_roundtrip.swift'
+
+    # =========================================================================
+    # First generate the pre-edit and post-edit Swift file and gather the edits
+    # and expected reparse regions. This is the parser for the special edit
+    # markup for testing incremental parsing
+    # =========================================================================
+
+    # Gather command line arguments for swift-syntax-test specifying the
+    # performed edits in this list
+    incremental_edit_args = []
+    reparse_args = []
+    try:
+        prepareForIncrParse(test_file=test_file, test_case=test_case,
+                            pre_edit_file=pre_edit_file,
+                            post_edit_file=post_edit_file,
+                            incremental_edit_args=incremental_edit_args,
+                            reparse_args=reparse_args)
+    except TestFailedError as e:
+        print('Test case "%s" of %s FAILed' % (test_case, test_file),
+              file=sys.stderr)
+        print(e.message, file=sys.stderr)
+        sys.exit(1)
+
+    try:
+        run_command([swiftsyntax_lit_test_helper, '-parse-incremental'] +
+                    ['-old-source-file', pre_edit_file] +
+                    ['-source-file', post_edit_file] +
+                    incremental_edit_args + reparse_args +
+                    ['-out', after_roundtrip_file])
+    except subprocess.CalledProcessError as e:
+        print('Test case "%s" of %s FAILed' % (test_case, test_file),
+              file=sys.stderr)
+        print('Parsing the swift file failed:\n', file=sys.stderr)
+        print(e.output.decode('UTF-8'), file=sys.stderr)
+        sys.exit(1)
+
+    # Check if the two syntax trees are the same
+    try:
+        run_command(
+            [
+                'diff', '-u',
+                post_edit_file,
+                after_roundtrip_file
+            ])
+    except subprocess.CalledProcessError as e:
+        print('Test case "%s" of %s FAILed' % (test_case, test_file),
+              file=sys.stderr)
+        print('Source file after incrementally parsing '
+              'does not match post-edit source file:\n\n',
+              file=sys.stderr)
+        print(e.output, file=sys.stderr)
+        sys.exit(1)
+
+
+if __name__ == '__main__':
+    main()