Compare Test Case

Quick Start

You'll typically receive a test case identifier and two branches. Follow these steps:

1. Run tuist test case show <id-or-identifier> --json to get the test case metrics.
2. Run tuist test case run list <identifier> --json to see runs across branches.
3. Compare behavior between base and head branches.
4. Inspect failures with tuist test case run show <run-id> --json.
5. Summarize findings with root cause analysis.

Step 1: Resolve the Test Case

By ID or dashboard URL

tuist test case show <test-case-id> --json

By identifier (Module/Suite/TestCase)

tuist test case show Module/Suite/TestCase --json

If no test case is provided

Discover flaky or failing tests to investigate:

tuist test case list --flaky --json --page-size 10

Key fields from the response:

• id -- unique identifier for subsequent commands
• name, module_name, suite_name -- the test identity
• reliability_rate -- percentage of successful runs
• flakiness_rate -- percentage of flaky runs in the last 30 days
• total_runs / failed_runs -- volume context
• is_flaky / is_quarantined -- current flags

Step 2: Get Runs on Each Branch

List test case runs filtered by the test case, and look at the git_branch field:

tuist test case run list <identifier> --json --page-size 20

Separate runs by branch. For each branch, compute:

• Pass rate: passed_runs / total_runs * 100
• Average duration
• Flaky run count
• Most recent status

Defaults

• If no base branch is provided, use the project's default branch (usually main).
• If no head branch is provided, detect the current git branch.

Step 3: Compare Branch Behavior

Metric	Base branch	Head branch	Verdict
Pass rate	e.g. 100%	e.g. 60%	REGRESSION
Avg duration	e.g. 0.5s	e.g. 2.1s	REGRESSION
Flaky runs	0	3	NEW FLAKINESS
Last status	success	failure	REGRESSION

Classify the change:

• Newly failing: 100% pass rate on base, <100% on head
• Newly flaky: No flaky runs on base, flaky runs on head
• Duration regression: >50% increase in average duration
• Fixed: Failing on base, passing on head
• Stable: Same behavior on both branches

Step 4: Inspect Failures

For each failing run on the head branch:

tuist test case run show <test-case-run-id> --json

Examine:

• failures[].message -- the assertion or error message
• failures[].path -- source file path
• failures[].line_number -- exact line of failure
• failures[].issue_type -- type of issue
• repetitions -- shows retry behavior (e.g., pass-fail-pass means flaky)
• crash_report -- crash data if the test runner crashed

Step 5: Identify Root Cause

Based on the comparison:

Newly failing

• Check commits between base and head branches for changes to the test file or the code under test.
• Look at the failure message for clues about what changed.

Newly flaky

• Common patterns: timing/async issues, shared state, environment dependencies.
• Check if repetitions show intermittent pass/fail patterns.
• See the fix-flaky-tests skill for detailed flaky test analysis patterns.

Duration regression

• Check if setup/teardown time increased.
• Check if the test is doing more work (new assertions, larger data sets).
• Check if a dependency became slower.

Summary Format

Produce a summary with:

1. Test case info: Name, module, suite, overall reliability.
2. Base branch behavior: Pass rate, avg duration, flaky count.
3. Head branch behavior: Pass rate, avg duration, flaky count.
4. Verdict: What changed and classification.
5. Root cause: Hypothesis based on failure analysis.
6. Recommendations: Specific file paths, line numbers, and fix suggestions.

Example:

Test Case Comparison: AuthModuleTests/LoginTests/test_login_with_expired_token

Overall reliability: 85% (was 100% before head branch)

Base (main):
  Pass rate: 100% (15/15 runs)
  Avg duration: 0.3s
  Flaky: No

Head (feature/auth-refactor):
  Pass rate: 60% (3/5 runs)
  Avg duration: 0.5s
  Flaky: Yes (2 flaky runs)

Verdict: NEWLY FLAKY -- test was stable on main but intermittently fails on feature branch

Root cause: The auth refactor introduced an async token refresh that races with the
test's synchronous assertion. Failures show "Expected status 401, got nil" at
Tests/AuthModuleTests/LoginTests.swift:42, suggesting the response arrives before
the token refresh completes.

Recommendations:
- Add an await/expectation before the assertion at LoginTests.swift:42
- Consider mocking the token refresh to make the test deterministic

Done Checklist

• Resolved the test case identity
• Gathered runs on both branches
• Compared pass rates, durations, and flakiness
• Inspected failure details for failing runs
• Identified root cause with file paths and line numbers
• Provided actionable fix recommendations