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Testing CoverAgent Core Functionality in Codium-ai/cover-agent

This test suite validates the core functionality of the CoverAgent class, which handles test coverage analysis and generation in the Codium-ai/cover-agent project. It comprehensively tests argument parsing, file handling, and coverage reporting mechanisms.

Test Coverage Overview

The test suite provides extensive coverage of the CoverAgent class functionality:

Command-line argument parsing and validation
File path verification and error handling
Test file duplication and output management
Coverage report generation and validation
Maximum iteration handling with strict coverage requirements
Differential coverage analysis

Implementation Analysis

The testing approach employs pytest fixtures and unittest.mock for isolation:

Extensive use of @patch decorators for dependency mocking
Temporary file handling for file operation tests
Mock objects to simulate file system and coverage reporting
Assertion-based validation of expected behaviors

Technical Details

Testing infrastructure includes:

pytest framework for test execution
unittest.mock for dependency isolation
tempfile for temporary file management
argparse for command-line argument testing
Custom assertion patterns for error validation

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Comprehensive error case coverage
Isolated test cases with proper teardown
Meaningful assertion messages
Proper resource cleanup
Structured test organization
Mock usage for external dependencies

codium-ai/cover-agent

tests/test_CoverAgent.py

            
from cover_agent.CoverAgent import CoverAgent
from cover_agent.main import parse_args
from unittest.mock import patch, MagicMock
import argparse
import os
import pytest
import tempfile

import unittest
class TestCoverAgent:
    def test_parse_args(self):
        with patch(
            "sys.argv",
            [
                "program.py",
                "--source-file-path",
                "test_source.py",
                "--test-file-path",
                "test_file.py",
                "--code-coverage-report-path",
                "coverage_report.xml",
                "--test-command",
                "pytest",
                "--max-iterations",
                "10",
            ],
        ):
            args = parse_args()
            assert args.source_file_path == "test_source.py"
            assert args.test_file_path == "test_file.py"
            assert args.project_root == ""
            assert args.code_coverage_report_path == "coverage_report.xml"
            assert args.test_command == "pytest"
            assert args.test_command_dir == os.getcwd()
            assert args.included_files is None
            assert args.coverage_type == "cobertura"
            assert args.report_filepath == "test_results.html"
            assert args.desired_coverage == 90
            assert args.max_iterations == 10

    @patch("cover_agent.CoverAgent.UnitTestGenerator")
    @patch("cover_agent.CoverAgent.ReportGenerator")
    @patch("cover_agent.CoverAgent.os.path.isfile")
    def test_agent_source_file_not_found(
        self, mock_isfile, mock_report_generator, mock_unit_cover_agent
    ):
        args = argparse.Namespace(
            source_file_path="test_source.py",
            test_file_path="test_file.py",
            project_root="",
            code_coverage_report_path="coverage_report.xml",
            test_command="pytest",
            test_command_dir=os.getcwd(),
            included_files=None,
            coverage_type="cobertura",
            report_filepath="test_results.html",
            desired_coverage=90,
            max_iterations=10,
        )
        parse_args = lambda: args
        mock_isfile.return_value = False

        with patch("cover_agent.main.parse_args", parse_args):
            with pytest.raises(FileNotFoundError) as exc_info:
                agent = CoverAgent(args)

        assert (
            str(exc_info.value) == f"Source file not found at {args.source_file_path}"
        )

        mock_unit_cover_agent.assert_not_called()
        mock_report_generator.generate_report.assert_not_called()

    @patch("cover_agent.CoverAgent.os.path.exists")
    @patch("cover_agent.CoverAgent.os.path.isfile")
    @patch("cover_agent.CoverAgent.UnitTestGenerator")
    def test_agent_test_file_not_found(
        self, mock_unit_cover_agent, mock_isfile, mock_exists
    ):
        args = argparse.Namespace(
            source_file_path="test_source.py",
            test_file_path="test_file.py",
            project_root="",
            code_coverage_report_path="coverage_report.xml",
            test_command="pytest",
            test_command_dir=os.getcwd(),
            included_files=None,
            coverage_type="cobertura",
            report_filepath="test_results.html",
            desired_coverage=90,
            max_iterations=10,
            prompt_only=False,
        )
        parse_args = lambda: args
        mock_isfile.side_effect = [True, False]
        mock_exists.return_value = True

        with patch("cover_agent.main.parse_args", parse_args):
            with pytest.raises(FileNotFoundError) as exc_info:
                agent = CoverAgent(args)

        assert str(exc_info.value) == f"Test file not found at {args.test_file_path}"

    @patch("cover_agent.CoverAgent.shutil.copy")
    @patch("cover_agent.CoverAgent.os.path.isfile", return_value=True)
    def test_duplicate_test_file_with_output_path(self, mock_isfile, mock_copy):
        with tempfile.NamedTemporaryFile(suffix=".py", delete=False) as temp_source_file:
            with tempfile.NamedTemporaryFile(suffix=".py", delete=False) as temp_test_file:
                args = argparse.Namespace(
                    source_file_path=temp_source_file.name,
                    test_file_path=temp_test_file.name,
                    project_root="",
                    test_file_output_path="output_test_file.py",  # This will be the path where output is copied
                    code_coverage_report_path="coverage_report.xml",
                    test_command="echo hello",
                    test_command_dir=os.getcwd(),
                    included_files=None,
                    coverage_type="cobertura",
                    report_filepath="test_results.html",
                    desired_coverage=90,
                    max_iterations=10,
                    additional_instructions="",
                    model="openai/test-model",
                    api_base="openai/test-api",
                    use_report_coverage_feature_flag=False,
                    log_db_path="",
                    diff_coverage=False,
                    branch="main",
                    run_tests_multiple_times=1,
                )

                with pytest.raises(AssertionError) as exc_info:
                    agent = CoverAgent(args)
                    failed_test_runs = agent.test_validator.get_coverage()
                    agent.test_gen.build_prompt(failed_test_runs)
                    agent._duplicate_test_file()

                assert "Fatal: Coverage report" in str(exc_info.value)
                mock_copy.assert_called_once_with(args.test_file_path, args.test_file_output_path)

        # Clean up the temp files
        os.remove(temp_source_file.name)
        os.remove(temp_test_file.name)

    @patch("cover_agent.CoverAgent.os.path.isfile", return_value=True)
    def test_duplicate_test_file_without_output_path(self, mock_isfile):
        with tempfile.NamedTemporaryFile(suffix=".py", delete=False) as temp_source_file:
            with tempfile.NamedTemporaryFile(suffix=".py", delete=False) as temp_test_file:
                args = argparse.Namespace(
                    source_file_path=temp_source_file.name,
                    test_file_path=temp_test_file.name,
                    project_root="",
                    test_file_output_path="",  # No output path provided
                    code_coverage_report_path="coverage_report.xml",
                    test_command="echo hello",
                    test_command_dir=os.getcwd(),
                    included_files=None,
                    coverage_type="cobertura",
                    report_filepath="test_results.html",
                    desired_coverage=90,
                    max_iterations=10,
                    additional_instructions="",
                    model="openai/test-model",
                    api_base="openai/test-api",
                    use_report_coverage_feature_flag=False,
                    log_db_path="",
                    diff_coverage=False,
                    branch="main",
                    run_tests_multiple_times=1,
                )

                with pytest.raises(AssertionError) as exc_info:
                    agent = CoverAgent(args)
                    failed_test_runs = agent.test_validator.get_coverage()
                    agent.test_gen.build_prompt(failed_test_runs)
                    agent._duplicate_test_file()

                assert "Fatal: Coverage report" in str(exc_info.value)
                assert args.test_file_output_path == args.test_file_path

        # Clean up the temp files
        os.remove(temp_source_file.name)
        os.remove(temp_test_file.name)

    @patch("cover_agent.CoverAgent.os.environ", {})
    @patch("cover_agent.CoverAgent.sys.exit")
    @patch("cover_agent.CoverAgent.UnitTestGenerator")
    @patch("cover_agent.CoverAgent.UnitTestValidator")
    @patch("cover_agent.CoverAgent.UnitTestDB")
    def test_run_max_iterations_strict_coverage(self, mock_test_db, mock_unit_test_validator, mock_unit_test_generator, mock_sys_exit):
        with tempfile.NamedTemporaryFile(suffix=".py", delete=False) as temp_source_file:
            with tempfile.NamedTemporaryFile(suffix=".py", delete=False) as temp_test_file:
                args = argparse.Namespace(
                    source_file_path=temp_source_file.name,
                    test_file_path=temp_test_file.name,
                    project_root="",
                    test_file_output_path="output_test_file.py",
                    code_coverage_report_path="coverage_report.xml",
                    test_command="pytest",
                    test_command_dir=os.getcwd(),
                    included_files=None,
                    coverage_type="cobertura",
                    report_filepath="test_results.html",
                    desired_coverage=90,
                    max_iterations=1,
                    additional_instructions="",
                    model="openai/test-model",
                    api_base="openai/test-api",
                    use_report_coverage_feature_flag=False,
                    log_db_path="",
                    run_tests_multiple_times=False,
                    strict_coverage=True,
                    diff_coverage=False,
                    branch="main"
                )
                # Mock the methods used in run
                validator = mock_unit_test_validator.return_value
                validator.current_coverage = 0.5  # below desired coverage
                validator.desired_coverage = 90
                validator.get_coverage.return_value = [{}, "python", "pytest", ""]
                generator = mock_unit_test_generator.return_value
                generator.generate_tests.return_value = {"new_tests": [{}]}
                agent = CoverAgent(args)
                agent.run()
                # Assertions to ensure sys.exit was called
                mock_sys_exit.assert_called_once_with(2)
                mock_test_db.return_value.dump_to_report.assert_called_once_with(args.report_filepath)

    @patch("cover_agent.CoverAgent.os.path.isfile", return_value=True)
    @patch("cover_agent.CoverAgent.os.path.isdir", return_value=False)
    def test_project_root_not_found(self, mock_isdir, mock_isfile):
        args = argparse.Namespace(
            source_file_path="test_source.py",
            test_file_path="test_file.py",
            project_root="/nonexistent/path",
            test_file_output_path="",
            code_coverage_report_path="coverage_report.xml",
            test_command="pytest",
            test_command_dir=os.getcwd(),
            included_files=None,
            coverage_type="cobertura",
            report_filepath="test_results.html",
            desired_coverage=90,
            max_iterations=10
        )
        
        with pytest.raises(FileNotFoundError) as exc_info:
            agent = CoverAgent(args)
            
        assert str(exc_info.value) == f"Project root not found at {args.project_root}"

    @patch("cover_agent.CoverAgent.UnitTestValidator")
    @patch("cover_agent.CoverAgent.UnitTestGenerator")
    @patch("cover_agent.CoverAgent.UnitTestDB")
    @patch("cover_agent.CoverAgent.CustomLogger")
    def test_run_diff_coverage(self, mock_logger, mock_test_db, mock_test_gen, mock_test_validator):
        with tempfile.NamedTemporaryFile(suffix=".py", delete=False) as temp_source_file:
            with tempfile.NamedTemporaryFile(suffix=".py", delete=False) as temp_test_file:
                args = argparse.Namespace(
                    source_file_path=temp_source_file.name,
                    test_file_path=temp_test_file.name,
                    project_root="",
                    test_file_output_path="output_test_file.py",
                    code_coverage_report_path="coverage_report.xml",
                    test_command="pytest",
                    test_command_dir=os.getcwd(),
                    included_files=None,
                    coverage_type="cobertura",
                    report_filepath="test_results.html",
                    desired_coverage=90,
                    max_iterations=1,
                    additional_instructions="",
                    model="openai/test-model",
                    api_base="openai/test-api",
                    use_report_coverage_feature_flag=False,
                    log_db_path="",
                    run_tests_multiple_times=False,
                    strict_coverage=False,
                    diff_coverage=True,
                    branch="main"
                )
                mock_test_validator.return_value.current_coverage = 0.5
                mock_test_validator.return_value.desired_coverage = 90
                mock_test_validator.return_value.get_coverage.return_value = [{}, "python", "pytest", ""]
                mock_test_gen.return_value.generate_tests.return_value = {"new_tests": [{}]}
                agent = CoverAgent(args)
                agent.run()
                mock_logger.get_logger.return_value.info.assert_any_call(
                    f"Current Diff Coverage: {round(mock_test_validator.return_value.current_coverage * 100, 2)}%"
                )

        # Clean up the temp files
        os.remove(temp_source_file.name)
        os.remove(temp_test_file.name)