"""Regression tests for false green results in the changed-code coverage gate.

Copyright (C) 2004-2026 The Cacti Group. GPL-2.0-or-later.
"""
from contextlib import redirect_stdout
import importlib.util
import io
import json
from pathlib import Path
import tempfile
import unittest
import sys
from unittest.mock import patch

sys.dont_write_bytecode = True
SPEC = importlib.util.spec_from_file_location('coverage_gate', Path(__file__).with_name('report_changed_coverage.py'))
GATE = importlib.util.module_from_spec(SPEC)
SPEC.loader.exec_module(GATE)


class CoverageEvidenceTest(unittest.TestCase):
    def test_deletion_only_files_do_not_require_added_line_coverage(self):
        diff = '--- a/lib/old.php\n+++ b/lib/old.php\n@@ -3 +2,0 @@\n-return true;\n'
        with patch.object(GATE.subprocess, 'check_output', side_effect=['base', diff]):
            self.assertEqual(GATE.added_lines('HEAD^'), {})

    def test_deleted_file_headers_do_not_become_added_source_lines(self):
        diff = ('diff --git a/old.css b/old.css\n--- a/old.css\n+++ /dev/null\n'
                '@@ -1 +0,0 @@\n-body { color: red; }\n'
                'diff --git a/current.css b/current.css\n--- a/current.css\n'
                '+++ b/current.css\n@@ -0,0 +1 @@\n+body { color: blue; }\n'
                'diff --git a/last.css b/last.css\n--- a/last.css\n'
                '+++ /dev/null\n@@ -1 +0,0 @@\n-body { color: red; }\n')
        with patch.object(GATE.subprocess, 'check_output', side_effect=['base', diff]):
            self.assertEqual(GATE.added_lines('HEAD^'), {'current.css': {1}})

    def evaluate(self, evidence, added=(3,), minimum=None):
        with tempfile.TemporaryDirectory() as temporary:
            root = Path(temporary)
            (root / 'lib').mkdir()
            source = root / 'lib/example.php'
            source.write_text('<?php\nfunction example() {\nreturn true;\n}\n')
            coverage = root / 'coverage.json'
            coverage.write_text(json.dumps({str(source): {'lines': evidence}} if evidence is not None else {}))
            arguments = ['gate', '--base', 'HEAD', '--php-coverage', str(coverage)]
            if minimum is not None:
                arguments += ['--minimum', str(minimum)]
            with patch.object(GATE.Path, 'cwd', return_value=root), patch.object(GATE, 'added_lines', return_value={'lib/example.php': set(added)}), patch('sys.argv', arguments), redirect_stdout(io.StringIO()):
                return GATE.main()

    def test_covered_statement_passes(self):
        self.assertEqual(self.evaluate({3: 1}), 0)

    def test_unexecuted_statement_fails(self):
        self.assertEqual(self.evaluate({3: -1}), 1)

    def test_missing_file_evidence_fails(self):
        self.assertEqual(self.evaluate(None), 1)

    def test_partial_file_instrumentation_fails(self):
        self.assertEqual(self.evaluate({2: 1}), 1)

    def test_dead_opcode_is_excluded(self):
        self.assertEqual(self.evaluate({3: -2}), 0)

    def test_explicit_threshold_preserves_the_default_security_gate(self):
        self.assertEqual(self.evaluate({2: 1, 3: -1}, (2, 3)), 1)
        self.assertEqual(self.evaluate({2: 1, 3: -1}, (2, 3), 50), 0)
        self.assertEqual(self.evaluate({2: 1, 3: -1}, (2, 3), 80), 1)

    def test_lower_threshold_does_not_allow_missing_evidence(self):
        self.assertEqual(self.evaluate(None, minimum=80), 1)

    def test_no_changed_lines_of_the_language_passes(self):
        # A PR that changes nothing in the gated language has nothing to cover,
        # so the gate must pass rather than fail closed on an empty report.
        with tempfile.TemporaryDirectory() as temporary:
            root = Path(temporary)
            arguments = ['gate', '--base', 'HEAD']
            with patch.object(GATE.Path, 'cwd', return_value=root), patch.object(GATE, 'added_lines', return_value={}), patch('sys.argv', arguments), redirect_stdout(io.StringIO()):
                self.assertEqual(GATE.main(), 0)


if __name__ == '__main__':
    unittest.main()