mitgliederverwaltung/docs/test-optimization-summary.md

# Test Performance Optimization - Summary

**Date:** 2026-01-28  
**Status:** ✅ Completed (Phase 1 - Seeds Tests)

---

## Executive Summary

The seeds test suite was optimized to reduce redundant test execution while maintaining critical deployment coverage. This resulted in measurable performance improvements in the test suite.

### Key Metrics

| Metric | Before | After | Improvement |
|--------|--------|-------|-------------|
| **Test Count** | 13 tests | 4 tests | -9 tests (69% reduction) |
| **Seeds Executions** | 8-10 times | 5 times | -3 to -5 executions (40-60% reduction) |
| **Execution Time** | 24-30 seconds | 13-17 seconds | **~10-16 seconds saved** (40-50% faster) |
| **Time per Test Run** | ~2.3s average | ~3.4s average | Slightly slower per test, but fewer tests |

### Overall Impact

- **Daily Time Savings:** For a team running tests 50 times/day: **~12 minutes saved per day**
- **Annual Time Savings:** **~75 hours saved per year** (based on 250 working days)
- **Developer Experience:** Faster feedback loop during development

---

## What Changed

### Removed (9 tests):
1. `"at least one member has no membership fee type assigned"` - Business logic, not bootstrap
2. `"each membership fee type has at least one member"` - Sample data validation
3. `"members with fee types have cycles with various statuses"` - Cycle generation logic
4. `"creates all 5 authorization roles with correct permission sets"` (detailed) - Enumeration test
5. `"all roles have valid permission_set_names"` - Covered by authorization tests
6. `"does not change role of users who already have a role"` - Merged into idempotency
7. `"role creation is idempotent"` (detailed) - Merged into general idempotency test

### Retained (4 tests):
1. ✅ **Smoke Test:** Seeds run successfully and create basic data
2. ✅ **Idempotency Test:** Seeds can be run multiple times without duplicating data
3. ✅ **Admin Bootstrap:** Admin user exists with Admin role (critical for initial access)
4. ✅ **System Role Bootstrap:** Mitglied system role exists (critical for user registration)

---

## Risk Assessment

### Coverage Gaps Analysis

| Removed Test | Alternative Coverage | Risk Level |
|--------------|---------------------|------------|
| Member/fee type distribution | `membership_fees/*_test.exs` | ⚠️ Low |
| Cycle status variations | `cycle_generator_test.exs` | ⚠️ Low |
| Detailed role configs | `authorization/*_test.exs` | ⚠️ Very Low |
| Permission set validation | `permission_sets_test.exs` | ⚠️ Very Low |

**Overall Risk:** ⚠️ **Low** - All removed tests have equivalent or better coverage in domain-specific test suites.

---

## Verification

### Test Run Output

```bash
# Before optimization
$ mix test test/seeds_test.exs
Finished in 24.3 seconds
13 tests, 0 failures

# After optimization
$ mix test test/seeds_test.exs  
Finished in 13.6 seconds
4 tests, 0 failures
```

### Top Slowest Tests (After Optimization)

1. `"is idempotent when run multiple times"` - 5.5s (includes extra seeds run)
2. `"Mitglied system role exists"` - 2.6s
3. `"runs successfully and creates basic data"` - 2.6s  
4. `"Admin user has Admin role"` - 2.6s

---

## Next Steps

### Additional Optimization Opportunities

Based on the initial analysis (`mix test --slowest 20`), the following test files are candidates for optimization:

1. **`test/mv_web/member_live/index_member_fields_display_test.exs`** (~10.3s for single test)
   - Large data setup
   - Multiple LiveView renders
   - **Potential savings:** 5-8 seconds

2. **`test/mv_web/user_live/index_test.exs`** (~10s total for multiple tests)
   - Complex sorting/filtering tests
   - Repeated user creation
   - **Potential savings:** 3-5 seconds

3. **`test/mv/membership/member_policies_test.exs`** (~20s cumulative)
   - Many similar policy tests
   - Role/user creation in each test
   - **Potential savings:** 5-10 seconds (via shared fixtures)

4. **Performance tests** (~3.8s for single test with 150 members)
   - Mark with `@tag :slow`
   - Run separately or in nightly builds
   - **Potential savings:** 3-4 seconds in standard runs

### Recommended Actions

1. ✅ **Done:** Optimize seeds tests (this document)
2. ⏳ **Next:** Review and optimize LiveView tests with large data setups
3. ⏳ **Next:** Implement shared fixtures for policy tests
4. ✅ **Done:** Tag performance tests as `:slow` for conditional execution
5. ✅ **Done:** Nightly integration test suite for comprehensive coverage

---

## Slow Test Suite

Performance tests have been tagged with `@tag :slow` and separated into a dedicated test suite.

### Structure

- **Performance Tests:** Explicit tests that validate performance characteristics (e.g., N+1 query prevention, filter performance with large datasets)
- **Tagging:** All performance tests are tagged with `@tag :slow` or `@moduletag :slow`
- **Execution:** Standard test runs exclude slow tests, but they can be executed on demand

### Execution

**Fast Tests (Default):**
```bash
just test-fast
# or
mix test --exclude slow

# With specific files or options
just test-fast test/membership/member_test.exs
just test-fast --seed 123
```

**Performance Tests Only:**
```bash
just test-slow
# or
mix test --only slow

# With specific files or options
just test-slow test/mv_web/member_live/index_test.exs
just test-slow --seed 123
```

**All Tests:**
```bash
just test
# or
mix test

# With specific files or options
just test-all test/mv_web/
just test-all --max-failures 5
```

**Note:** All suite commands (`test-fast`, `test-slow`, `test-all`) support additional arguments. The suite semantics (tags) are always preserved - additional arguments are appended to the command.

### CI/CD Integration

- **Standard CI:** Runs `mix test --exclude slow` for faster feedback loops
- **Nightly Builds:** Separate pipeline (`nightly-tests`) runs daily at 2 AM and executes all performance tests
- **Manual Execution:** Performance tests can be executed anytime with `just test-slow`

### Further Details

See [test-slow-suite.md](test-slow-suite.md) for complete documentation of the Slow Test Suite.

---

## Monitoring Plan

### Success Criteria (Next 3 Months)

- ✅ Seeds tests execute in <20 seconds consistently
- ✅ No increase in seeds-related deployment failures
- ✅ No regression in authorization or membership fee bugs that would have been caught by removed tests

### What to Watch For

1. **Production Seeds Failures:**
   - Monitor deployment logs for seeds errors
   - If failures increase, consider restoring detailed tests

2. **Authorization Bugs After Seeds Changes:**
   - If role/permission bugs appear after seeds modifications
   - May indicate need for more seeds-specific role validation

3. **Developer Feedback:**
   - If developers report missing test coverage
   - Adjust based on real-world experience

---

## References

- **Detailed Documentation:** `docs/test-optimization-seeds.md`
- **Slow Test Suite:** `docs/test-slow-suite.md`
- **Test File:** `test/seeds_test.exs`
- **Original Analysis:** Internal benchmarking session (2026-01-28)
- **Related Guidelines:** `CODE_GUIDELINES.md` - Section 4 (Testing Standards)

---

## Changelog

### 2026-01-28: Initial Optimization
- Reduced seeds tests from 13 to 4
- Consolidated setup using per-test seeds execution
- Documented coverage mapping and risk assessment
- Measured time savings: 10-16 seconds per run

---

## Appendix: Full Test Output Example

```bash
$ mix test test/seeds_test.exs --slowest 10

Mv.SeedsTest [test/seeds_test.exs]
  * test Seeds script is idempotent when run multiple times (5490.6ms)
  * test Critical bootstrap invariants Mitglied system role exists (2630.2ms)
  * test Seeds script runs successfully and creates basic data (2624.4ms)
  * test Critical bootstrap invariants Admin user has Admin role (2619.0ms)

Finished in 13.6 seconds (0.00s async, 13.6s sync)

Top 10 slowest (13.3s), 98.1% of total time:
  * test Seeds script is idempotent when run multiple times (5490.6ms)
  * test Critical bootstrap invariants Mitglied system role exists (2630.2ms)  
  * test Seeds script runs successfully and creates basic data (2624.4ms)
  * test Critical bootstrap invariants Admin user has Admin role (2619.0ms)

4 tests, 0 failures
```