[Feature]: Add unit tests for JSONSummaryReporter

[sajal004004]

Summary

The JSONSummaryReporter class (krkn_ai/reporter/json_summary_reporter.py) currently has zero unit test coverage. Both existing reporters GenerationsReporter and HealthCheckReporter have dedicated test files in tests/unit/reporter/, but test_json_summary_reporter.py does not exist.

Description

The JSONSummaryReporter was recently added to generate a unified results.json summary of Krkn-AI experiment runs. It consolidates run metadata, config summaries, fitness statistics, top-10 best scenarios, and per-generation fitness progression into a single file.

Despite being a critical component of the reporting pipeline (called from GeneticAlgorithm.save() at the end of every run), this reporter has no test coverage. Adding comprehensive unit tests will ensure correctness, prevent regressions, and maintain parity with the test coverage of the other two reporters.

Background and Context

The existing reporter test suite follows a consistent pattern:

• tests/unit/reporter/test_generations_reporter.py — 4 tests covering YAML/JSON output and graph generation
• tests/unit/reporter/test_health_check_reporter.py — 7 tests covering CSV reports, graph plotting, and fitness CSV writing

Both use shared fixtures from tests/conftest.py (temp_output_dir, mock_cluster_components) and construct test data using DummyScenario and CommandRunResult models. The new test file should follow the same conventions.

Current Code Analysis

JSONSummaryReporter (in krkn_ai/reporter/json_summary_reporter.py) has 3 public/private methods that need testing:

1. generate_summary() — Builds the full results dict with: run_id, seed, timestamps, duration, config summary, statistics (total/unique scenarios, best/avg fitness), best_scenarios list, and fitness_progression list.

2. _build_fitness_progression() — Iterates best_of_generation to create per-generation best/average fitness data.

3. _build_best_scenarios() — Sorts seen_population by fitness score and returns the top 10 with rank, scenario_id, generation, fitness_score, scenario_type, and parameters.

4. save() — Writes generate_summary() output to results.json.

Currently no file tests/unit/reporter/test_json_summary_reporter.py exists.

Issues Identified

1. Zero test coverage for JSONSummaryReporter — any regression will go undetected
2. No validation that generate_summary() produces the expected JSON structure
3. No edge-case testing (empty populations, single generation, zero fitness scores)
4. No verification that save() writes valid, parseable JSON to the correct path
5. Test coverage gap compared to the other two reporters which are well-tested

Problem

Without tests, changes to data models (CommandRunResult, FitnessResult, BaseScenario) or the reporter itself could silently break results.json generation. Since results.json is intended to be the primary machine-readable summary for downstream tools (including the planned interactive visualization from Issue #74), its correctness is critical.

Proposed Solution

Create a new test file tests/unit/reporter/test_json_summary_reporter.py following the same patterns as the existing reporter tests:

• Use temp_output_dir and DummyScenario fixtures from conftest.py
• Construct CommandRunResult objects with known fitness scores
• Build seen_population dicts and best_of_generation lists as test inputs
• Assert on the structure and values of the generated summary dict
• Verify file output from save()

Implementation Steps

No response

Acceptance Criteria

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Testing Checklist

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Benefits

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Alternatives Considered

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Related Documentation

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Additional Context

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[Ayush-Patel-56]

I had raised the PR for the fix, please look it out.