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Testing Coverage Report Processing Implementation in Codium-ai/cover-agent

A comprehensive test suite for the CoverageProcessor class that handles various code coverage report formats including Cobertura, JaCoCo, and LCOV. The tests verify the accurate parsing and processing of coverage data, package extraction, and error handling across different file types and scenarios.
Test Coverage Overview

The test suite provides extensive coverage of the CoverageProcessor class functionality, including:
Coverage report parsing for Cobertura, JaCoCo, and LCOV formats
Package and class name extraction for Java and Kotlin files
Error handling for unsupported formats and file operations
Edge cases like empty reports and invalid file paths
Implementation Analysis

The testing approach utilizes pytest’s powerful fixtures and mocking capabilities to isolate test cases.
Extensive use of pytest fixtures for setup and teardown
Mock objects to simulate file operations and XML parsing
Parametrized tests for different coverage formats
Integration with multiple coverage report types
Technical Details

Key technical components include:
pytest framework with monkeypatch and mocker utilities
XML parsing using ElementTree
File handling with mock objects
Coverage calculation algorithms
Support for Java, Kotlin, and Python file processing
Best Practices Demonstrated

The test suite exemplifies several testing best practices:
Comprehensive mock usage for external dependencies
Clear test case organization and naming
Thorough error case coverage
Modular test structure with fixtures
Detailed assertions and error messages
codium-ai/cover-agent

tests/test_CoverageProcessor.py
            
import pytest
import xml.etree.ElementTree as ET
from cover_agent.CoverageProcessor import CoverageProcessor


@pytest.fixture
def mock_xml_tree(monkeypatch):
    """
    Creates a mock function to simulate the ET.parse method, returning a mocked XML tree structure.
    """

    def mock_parse(file_path):
        # Mock XML structure for the test
        xml_str = """<coverage>
                        <packages>
                            <package>
                                <classes>
                                    <class filename="app.py">
                                        <lines>
                                            <line number="1" hits="1"/>
                                            <line number="2" hits="0"/>
                                        </lines>
                                    </class>
                                </classes>
                            </package>
                        </packages>
                     </coverage>"""
        root = ET.ElementTree(ET.fromstring(xml_str))
        return root

    monkeypatch.setattr(ET, "parse", mock_parse)


class TestCoverageProcessor:
    @pytest.fixture
    def processor(self):
        # Initializes CoverageProcessor with cobertura coverage type for each test
        return CoverageProcessor("fake_path", "app.py", "cobertura")

    def test_parse_coverage_report_cobertura(self, mock_xml_tree, processor):
        """
        Tests the parse_coverage_report method for correct line number and coverage calculation with Cobertura reports.
        """
        covered_lines, missed_lines, coverage_pct = processor.parse_coverage_report()

        assert covered_lines == [1], "Should list line 1 as covered"
        assert missed_lines == [2], "Should list line 2 as missed"
        assert coverage_pct == 0.5, "Coverage should be 50 percent"

    def test_correct_parsing_for_matching_package_and_class(self, mocker):
        # Setup
        mock_open = mocker.patch(
            "builtins.open",
            mocker.mock_open(
                read_data="PACKAGE,CLASS,LINE_MISSED,LINE_COVERED
com.example,MyClass,5,10"
            ),
        )
        mocker.patch(
            "csv.DictReader",
            return_value=[
                {
                    "PACKAGE": "com.example",
                    "CLASS": "MyClass",
                    "LINE_MISSED": "5",
                    "LINE_COVERED": "10",
                }
            ],
        )
        processor = CoverageProcessor(
            "path/to/coverage_report.csv", "path/to/MyClass.java", "jacoco"
        )

        # Action
        missed, covered = processor.parse_missed_covered_lines_jacoco_csv(
            "com.example", "MyClass"
        )

        # Assert
        assert missed == 5
        assert covered == 10

    def test_returns_empty_lists_and_float(self, mocker):
        # Mocking the necessary methods
        mocker.patch(
            "cover_agent.CoverageProcessor.CoverageProcessor.extract_package_and_class_java",
            return_value=("com.example", "Example"),
        )
        mocker.patch(
            "cover_agent.CoverageProcessor.CoverageProcessor.parse_missed_covered_lines_jacoco_xml",
            return_value=(0, 0),
        )

        # Initialize the CoverageProcessor object
        coverage_processor = CoverageProcessor(
            file_path="path/to/coverage.xml",
            src_file_path="path/to/example.java",
            coverage_type="jacoco",
        )

        # Invoke the parse_coverage_report_jacoco method
        lines_covered, lines_missed, coverage_percentage = (
            coverage_processor.parse_coverage_report_jacoco()
        )

        # Assert the results
        assert lines_covered == [], "Expected lines_covered to be an empty list"
        assert lines_missed == [], "Expected lines_missed to be an empty list"
        assert coverage_percentage == 0, "Expected coverage percentage to be 0"

    def test_parse_coverage_report_unsupported_type(self):
        processor = CoverageProcessor("fake_path", "app.py", "unsupported_type")
        with pytest.raises(
            ValueError, match="Unsupported coverage report type: unsupported_type"
        ):
            processor.parse_coverage_report()

    def test_extract_package_and_class_java_file_error(self, mocker):
        mocker.patch("builtins.open", side_effect=FileNotFoundError("File not found"))
        processor = CoverageProcessor("fake_path", "path/to/MyClass.java", "jacoco")
        with pytest.raises(FileNotFoundError, match="File not found"):
            processor.extract_package_and_class_java()

    def test_extract_package_and_class_kotlin(self, mocker):
        kotlin_file_content = """
        package com.madrapps.playground
    
        import androidx.lifecycle.ViewModel

        class MainViewModel : ViewModel() {
        
            fun validate(userId: String): Boolean {
                return userId == "admin"
            }
        
            fun verifyAccess1(userId: String): Boolean {
                return userId == "super-admin"
            }
        
            fun verifyPassword(password: String): Boolean {
                return password.isNotBlank()
            }
        }
        """
        mocker.patch("builtins.open", mocker.mock_open(read_data=kotlin_file_content))
        processor = CoverageProcessor("fake_path", "path/to/MainViewModel.kt", "jacoco")
        package_name, class_name = processor.extract_package_and_class_kotlin()
        assert (
            package_name == "com.madrapps.playground"
        ), "Expected package name to be 'com.madrapps.playground'"
        assert class_name == "MainViewModel", "Expected class name to be 'MainViewModel'"

    def test_extract_package_and_class_java(self, mocker):
        java_file_content = """
        package com.example;

        public class MyClass {
            // class content
        }
        """
        mocker.patch("builtins.open", mocker.mock_open(read_data=java_file_content))
        processor = CoverageProcessor("fake_path", "path/to/MyClass.java", "jacoco")
        package_name, class_name = processor.extract_package_and_class_java()
        assert (
                package_name == "com.example"
        ), "Expected package name to be 'com.example'"
        assert class_name == "MyClass", "Expected class name to be 'MyClass'"

    def test_verify_report_update_file_not_updated(self, mocker):
        mocker.patch("os.path.exists", return_value=True)
        mocker.patch("os.path.getmtime", return_value=1234567.0)

        processor = CoverageProcessor("fake_path", "app.py", "cobertura")
        with pytest.raises(
            AssertionError,
            match="Fatal: The coverage report file was not updated after the test command.",
        ):
            processor.verify_report_update(1234567890)

    def test_verify_report_update_file_not_exist(self, mocker):
        mocker.patch("os.path.exists", return_value=False)

        processor = CoverageProcessor("fake_path", "app.py", "cobertura")
        with pytest.raises(
            AssertionError,
            match='Fatal: Coverage report "fake_path" was not generated.',
        ):
            processor.verify_report_update(1234567890)

    def test_process_coverage_report(self, mocker):
        mock_verify = mocker.patch(
            "cover_agent.CoverageProcessor.CoverageProcessor.verify_report_update"
        )
        mock_parse = mocker.patch(
            "cover_agent.CoverageProcessor.CoverageProcessor.parse_coverage_report",
            return_value=([], [], 0.0),
        )

        processor = CoverageProcessor("fake_path", "app.py", "cobertura")
        result = processor.process_coverage_report(1234567890)

        mock_verify.assert_called_once_with(1234567890)
        mock_parse.assert_called_once()
        assert result == ([], [], 0.0), "Expected result to be ([], [], 0.0)"

    def test_parse_missed_covered_lines_jacoco_csv_key_error(self, mocker):
        mock_open = mocker.patch(
            "builtins.open",
            mocker.mock_open(
                read_data="PACKAGE,CLASS,LINE_MISSED,LINE_COVERED
com.example,MyClass,5,10"
            ),
        )
        mocker.patch(
            "csv.DictReader",
            return_value=[
                {"PACKAGE": "com.example", "CLASS": "MyClass", "LINE_MISSED": "5"}
            ],
        )  # Missing 'LINE_COVERED'

        processor = CoverageProcessor(
            "path/to/coverage_report.csv", "path/to/MyClass.java", "jacoco"
        )

        with pytest.raises(KeyError):
            processor.parse_missed_covered_lines_jacoco_csv("com.example", "MyClass")

    def test_parse_coverage_report_lcov_no_coverage_data(self, mocker):
        """
        Test parse_coverage_report_lcov returns empty lists and 0 coverage when the lcov report contains no relevant data.
        """
        mocker.patch("builtins.open", mocker.mock_open(read_data=""))
        processor = CoverageProcessor("empty_report.lcov", "app.py", "lcov")
        covered_lines, missed_lines, coverage_pct = processor.parse_coverage_report_lcov()
        assert covered_lines == [], "Expected no covered lines"
        assert missed_lines == [], "Expected no missed lines"
        assert coverage_pct == 0, "Expected 0% coverage"

    def test_parse_coverage_report_lcov_with_coverage_data(self, mocker):
        """
        Test parse_coverage_report_lcov correctly parses coverage data from an lcov report.
        """
        lcov_data = """
        SF:app.py
        DA:1,1
        DA:2,0
        DA:3,1
        end_of_record
        """
        mocker.patch("builtins.open", mocker.mock_open(read_data=lcov_data))
        processor = CoverageProcessor("report.lcov", "app.py", "lcov")
        covered_lines, missed_lines, coverage_pct = processor.parse_coverage_report_lcov()
        assert covered_lines == [1, 3], "Expected lines 1 and 3 to be covered"
        assert missed_lines == [2], "Expected line 2 to be missed"
        assert coverage_pct == 2/3, "Expected 66.67% coverage"

    def test_parse_coverage_report_lcov_with_multiple_files(self, mocker):
        """
        Test parse_coverage_report_lcov correctly parses coverage data for the target file among multiple files in the lcov report.
        """
        lcov_data = """
        SF:other.py
        DA:1,1
        DA:2,0
        end_of_record
        SF:app.py
        DA:1,1
        DA:2,0
        DA:3,1
        end_of_record
        SF:another.py
        DA:1,1
        end_of_record
        """
        mocker.patch("builtins.open", mocker.mock_open(read_data=lcov_data))
        processor = CoverageProcessor("report.lcov", "app.py", "lcov")
        covered_lines, missed_lines, coverage_pct = processor.parse_coverage_report_lcov()
        assert covered_lines == [1, 3], "Expected lines 1 and 3 to be covered for app.py"
        assert missed_lines == [2], "Expected line 2 to be missed for app.py"
        assert coverage_pct == 2/3, "Expected 66.67% coverage for app.py"

    def test_parse_coverage_report_unsupported_type(self, mocker):
        mocker.patch(
            "cover_agent.CoverageProcessor.CoverageProcessor.extract_package_and_class_java",
            return_value=("com.example", "Example"),
        )

        processor = CoverageProcessor(
            "path/to/coverage_report.html", "path/to/MyClass.java", "jacoco"
        )
        with pytest.raises(
            ValueError, match="Unsupported JaCoCo code coverage report format: html"
        ):
            processor.parse_coverage_report_jacoco()

    def test_parse_missed_covered_lines_jacoco_xml_no_source_file(self, mocker):
        #, mock_xml_tree
        mocker.patch(
            "cover_agent.CoverageProcessor.CoverageProcessor.extract_package_and_class_java",
            return_value=("com.example", "Example"),
        )

        xml_str = """<report>
                        <package name="path/to">
                            <sourcefile name="MyClass.java">
                                <counter type="INSTRUCTION" missed="53" covered="387"/>
                                <counter type="BRANCH" missed="2" covered="6"/>
                                <counter type="LINE" missed="9" covered="94"/>
                                <counter type="COMPLEXITY" missed="5" covered="23"/>
                                <counter type="METHOD" missed="3" covered="21"/>
                                <counter type="CLASS" missed="0" covered="1"/>
                            </sourcefile>
                        </package>
                    </report>"""

        mocker.patch(
            "xml.etree.ElementTree.parse",
            return_value=ET.ElementTree(ET.fromstring(xml_str))
        )

        processor = CoverageProcessor(
            "path/to/coverage_report.xml", "path/to/MySecondClass.java", "jacoco"
        )

        # Action
        missed, covered = processor.parse_missed_covered_lines_jacoco_xml(
            "MySecondClass"
        )

        # Assert
        assert missed == 0
        assert covered == 0

    def test_parse_missed_covered_lines_jacoco_xml(self, mocker):
        #, mock_xml_tree
        mocker.patch(
            "cover_agent.CoverageProcessor.CoverageProcessor.extract_package_and_class_java",
            return_value=("com.example", "Example"),
        )

        xml_str = """<report>
                        <package name="path/to">
                            <sourcefile name="MyClass.java">
                                <counter type="INSTRUCTION" missed="53" covered="387"/>
                                <counter type="BRANCH" missed="2" covered="6"/>
                                <counter type="LINE" missed="9" covered="94"/>
                                <counter type="COMPLEXITY" missed="5" covered="23"/>
                                <counter type="METHOD" missed="3" covered="21"/>
                                <counter type="CLASS" missed="0" covered="1"/>
                            </sourcefile>
                        </package>
                    </report>"""

        mocker.patch(
            "xml.etree.ElementTree.parse",
            return_value=ET.ElementTree(ET.fromstring(xml_str))
        )

        processor = CoverageProcessor(
            "path/to/coverage_report.xml", "path/to/MyClass.java", "jacoco"
        )

        # Action
        missed, covered = processor.parse_missed_covered_lines_jacoco_xml(
            "MyClass"
        )

        # Assert
        assert missed == 9
        assert covered == 94

    def test_parse_missed_covered_lines_kotlin_jacoco_xml(self, mocker):
        #, mock_xml_tree
        mocker.patch(
            "cover_agent.CoverageProcessor.CoverageProcessor.extract_package_and_class_kotlin",
            return_value=("com.example", "Example"),
        )

        xml_str = """<report>
                        <package name="path/to">
                            <sourcefile name="MyClass.kt">
                                <counter type="INSTRUCTION" missed="53" covered="387"/>
                                <counter type="BRANCH" missed="2" covered="6"/>
                                <counter type="LINE" missed="9" covered="94"/>
                                <counter type="COMPLEXITY" missed="5" covered="23"/>
                                <counter type="METHOD" missed="3" covered="21"/>
                                <counter type="CLASS" missed="0" covered="1"/>
                            </sourcefile>
                        </package>
                    </report>"""

        mocker.patch(
            "xml.etree.ElementTree.parse",
            return_value=ET.ElementTree(ET.fromstring(xml_str))
        )

        processor = CoverageProcessor(
            "path/to/coverage_report.xml", "path/to/MyClass.kt", "jacoco"
        )

        # Action
        missed, covered = processor.parse_missed_covered_lines_jacoco_xml(
            "MyClass"
        )

        # Assert
        assert missed == 9
        assert covered == 94

    def test_get_file_extension_with_valid_file_extension(self):
        processor = CoverageProcessor(
            "path/to/coverage_report.xml", "path/to/MyClass.java", "jacoco"
        )

        file_extension = processor.get_file_extension("coverage_report.xml")

        # Assert
        assert file_extension == 'xml'

    def test_get_file_extension_with_no_file_extension(self):
        processor = CoverageProcessor(
            "path/to/coverage_report", "path/to/MyClass.java", "jacoco"
        )

        file_extension = processor.get_file_extension("coverage_report")

        # Assert
        assert file_extension is ''

    def test_parse_coverage_report_lcov_with_feature_flag(self, mocker):
        mock_parse_lcov = mocker.patch("cover_agent.CoverageProcessor.CoverageProcessor.parse_coverage_report_lcov", return_value=([], [], 0.0))
        processor = CoverageProcessor("fake_path", "app.py", "lcov", use_report_coverage_feature_flag=True)
        result = processor.parse_coverage_report()
        mock_parse_lcov.assert_called_once()
        assert result == ([], [], 0.0), "Expected result to be ([], [], 0.0)"


    def test_parse_coverage_report_cobertura_with_feature_flag(self, mocker):
        mock_parse_cobertura = mocker.patch("cover_agent.CoverageProcessor.CoverageProcessor.parse_coverage_report_cobertura", return_value=([], [], 0.0))
        processor = CoverageProcessor("fake_path", "app.py", "cobertura", use_report_coverage_feature_flag=True)
        result = processor.parse_coverage_report()
        mock_parse_cobertura.assert_called_once()
        assert result == ([], [], 0.0), "Expected result to be ([], [], 0.0)"


    def test_parse_coverage_report_jacoco(self, mocker):
        mock_parse_jacoco = mocker.patch("cover_agent.CoverageProcessor.CoverageProcessor.parse_coverage_report_jacoco", return_value=([], [], 0.0))
        processor = CoverageProcessor("fake_path", "app.py", "jacoco", use_report_coverage_feature_flag=True)
        result = processor.parse_coverage_report()
        mock_parse_jacoco.assert_called_once()
        assert result == ([], [], 0.0), "Expected result to be ([], [], 0.0)"


    def test_parse_coverage_report_cobertura_filename_not_found(self, mock_xml_tree, processor):
        covered_lines, missed_lines, coverage_pct = processor.parse_coverage_report_cobertura("non_existent_file.py")
        assert covered_lines == [], "Expected no covered lines"
        assert missed_lines == [], "Expected no missed lines"
        assert coverage_pct == 0.0, "Expected 0% coverage"


    def test_parse_coverage_report_lcov_file_read_error(self, mocker):
        mocker.patch("builtins.open", side_effect=IOError("File read error"))
        processor = CoverageProcessor("report.lcov", "app.py", "lcov")
        with pytest.raises(IOError, match="File read error"):
            processor.parse_coverage_report_lcov()


    def test_parse_coverage_report_cobertura_all_files(self, mock_xml_tree, processor):
        coverage_data = processor.parse_coverage_report_cobertura()
        expected_data = {
            "app.py": ([1], [2], 0.5)
        }
        assert coverage_data == expected_data, "Expected coverage data for all files"


    def test_parse_coverage_report_unsupported_type_with_feature_flag(self):
        processor = CoverageProcessor("fake_path", "app.py", "unsupported_type", use_report_coverage_feature_flag=True)
        with pytest.raises(ValueError, match="Unsupported coverage report type: unsupported_type"):
            processor.parse_coverage_report()

    def test_parse_coverage_report_jacoco_without_feature_flag(self, mocker):
        mock_parse_jacoco = mocker.patch(
            "cover_agent.CoverageProcessor.CoverageProcessor.parse_coverage_report_jacoco",
            return_value=([], [], 0.0)
        )
        processor = CoverageProcessor("fake_path", "app.py", "jacoco", use_report_coverage_feature_flag=False)
        result = processor.parse_coverage_report()
        mock_parse_jacoco.assert_called_once()
        assert result == ([], [], 0.0), "Expected result to be ([], [], 0.0)"

    def test_parse_coverage_report_unsupported_type_without_feature_flag(self):
        processor = CoverageProcessor("fake_path", "app.py", "unsupported_type", use_report_coverage_feature_flag=False)
        with pytest.raises(ValueError, match="Unsupported coverage report type: unsupported_type"):
            processor.parse_coverage_report()



    def test_parse_coverage_report_lcov_without_feature_flag(self, mocker):
        mock_parse_lcov = mocker.patch(
            "cover_agent.CoverageProcessor.CoverageProcessor.parse_coverage_report_lcov",
            return_value=([], [], 0.0)
        )
        processor = CoverageProcessor("fake_path", "app.py", "lcov", use_report_coverage_feature_flag=False)
        result = processor.parse_coverage_report()
        mock_parse_lcov.assert_called_once()
        assert result == ([], [], 0.0), "Expected result to be ([], [], 0.0)"