Fix find_tests line-number search for test names at the start of a line

[joniumGit]

Mandatory 🍍

UnityTestRunnerGenerator#find_tests in auto/generate_test_runner.rb locates each test's line number with a forward cursor and the regex /\s+#{name}(?:\s|\()/. The leading \s+ (added in f278c18 for #288) requires whitespace before the name on the same line, so a definition written as

void
test_something(void)

never matches its own line. Two things follow:

• every such test is reported with line_number 0 in the generated runner;
• the cursor scans to the end of the file for every test, so the search is O(tests x lines) with the interpolated regex recompiled on each line.

On a 10,000-line file with 367 tests this costs about 14 s of Ruby time per file on an Apple M-series laptop (Ruby 2.6 and 4.0), and 20 s or more on typical CI runners. Projects that write the return type on its own line hit this on every runner generation, including through Ceedling, which vendors this file.

Change

• Accept start-of-line as well as whitespace before the name: /(?:^|\s)#{name}(?:\s|\()/.
• Build the regex once per test instead of once per line.
• The trailing (?:\s|\() is unchanged, so the partial-name case from Invalid line number in runner generator in very specific case #288 (test_my_function vs test_my_function_invalid_behavior) still resolves to the right line.

Tests

Two cases added to test/tests/test_generate_test_runner.rb:

• FindTestsLineNumbersWhenNameStartsTheLine: names at column 0 get their real line numbers. Fails before this change (both reported as 0), passes after.
• FindTestsLineNumbersWhenOneNameIsAPrefixOfAnother: the Invalid line number in runner generator in very specific case #288 case, passes before and after.

cd test && rake test:scripts: 69/69 before, 71/71 after. rubocop ../auto/generate_test_runner.rb --config .rubocop.yml (1.57.2, as in CI): no offenses.

Measurement

Synthetic file, 367 tests of 25 lines each in the void / test_x(void) style, 11,015 lines, one find_tests call:

Ruby	before	after	line numbers found
2.6.10	13.5 s	0.28 s	0/367 -> 367/367
4.0.2	14.0 s	0.27 s	0/367 -> 367/367

Reproduction (from the repository root, before and after this change):

ruby -e '
  src = "#include \"unity.h\"\n\n"
  367.times { |i| src << "void\ntest_case_#{i}(void)\n{\n" << "    TEST_ASSERT_EQUAL(1, 1);\n" * 25 << "}\n\n" }
  require "./auto/generate_test_runner"
  t0 = Process.clock_gettime(Process::CLOCK_MONOTONIC)
  tests = UnityTestRunnerGenerator.new({}).find_tests(src)
  printf("%.2f s, line numbers found: %d/%d\n", Process.clock_gettime(Process::CLOCK_MONOTONIC) - t0, tests.count { |t| t[:line_number] > 0 }, tests.size)
'

Notes

The regex has had this form in every tag from v2.4.2 to v2.7.0 and on current master. I found no existing issue or PR about it.
I used Claude Code in making this PR.