fix(formatter): show full error message for test failures (#690)

[ousamabenyounes]

Problem

format_compact() truncated all test failure error messages to 2 lines via .take(2). Playwright errors look like:

Error: expect(locator).toHaveText(expected)   ← line 1 (visible)
                                               ← line 2 (visible, empty)
Expected: 'Submit'                             ← cut here
Received: 'Loading'                            ← cut here
Call log:                                      ← cut here
  - waiting for getByRole('button', ...)       ← cut here

Agents saw only "Error: expect(locator).toHaveText(expected)" — no diff, no call log, nothing actionable. This caused the 170 tool calls / 3.6M token loop described in #690.

Fix

Replace .take(2).join(" ") with a full line-by-line iteration of error_message. The summary line (PASS (28) FAIL (2)) stays compact. Only the per-failure detail is now fully preserved.

// Before
let error_preview: String = failure.error_message.lines().take(2).collect::<Vec<_>>().join(" ");
lines.push(format!("   {}", error_preview));

// After
for line in failure.error_message.lines() {
    lines.push(format!("   {}", line));
}

Impact

Affects all test runners using TestResult: Playwright, Vitest, Cargo test, Pytest, .NET — any test failure is now fully visible in compact mode.

Tests

4 new unit tests in formatter.rs:

• test_compact_shows_full_error_message — asserts expected/received diff and call log are present
• test_compact_summary_line_is_concise — summary stays on one line
• test_compact_all_pass_is_one_line — success output stays compact
• test_compact_single_line_error_no_trailing_noise — single-line errors still work

cargo test parser::formatter::tests
✓ 4 passed
cargo test
✓ 983 passed, 0 failed

Closes #690

[aeppling]

Hello Ousama !

Thanks for contributing again :)

The truncation fix is of course correct, but PR 690 also asked for pass-through mechanism like others commands,

One thing missing : playwright_cmd.rs is the only test runner that doesn't call tee_and_hint, which is RTK mechanism for pass-through on failure, used by vitest, pytest, cargo, go, etc.

That was asked in #690, could you maybe fix this little as well so we resolve the full issue ?

Should be easy to add and straght-forward to merge after

[aeppling]

If no news from you, i'll merge what you have done, it solve a part of the issue, but i'll not be able to close the issue if not totally resolved.

Thanks again for solving issues

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