Analyzing how pytest works from a pytest source code perspective

Analyzing how pytest works from the perspective of pytest source code

through (a gap)pytest To analyze how it works from the perspective of the source code, we need to focus on a few key sections, especially thepytest the startup process and the collection and execution of tests. Below is a description of the process based on thepytest A high-level overview of the source code.

The pytest startup process

1. Command line parsing.

   • pytest The entry point to the in the file() function.
   • In this function, it first passes the.get_config() Get configuration.
   • follow with() to parse command line arguments.

2. Configuration loading.

   • pytest will recursively look for configuration files in the current directory and its parent directory, for example maybe。
   • utilization class to store configuration information.

3. Plugin Management.

   • pass (a bill or inspection etc) cap (a poem) to manage plugins.
   • Plugins can be registered and called at various stages.

Test collection process

1. Collector initialization.

   • pytest utilization module to handle test collection.
   • Session.from_parent method creates a newSession Example.
   • Collector.from_parent method is used to build the collector tree.

2. Test file found.

   • pytest pass (a bill or inspection etc)Session.perform_collect method to traverse the directory structure and discover test modules.
   • File.from_parent method is used to create theFile instance to represent the test file.
   • Function.from_parent method is used to create theFunction instance to represent the test function.

3. Test Item Construction.

   • Once the test file has been found, it is passed through thecollect method to collect the test functions in the file.
   • The test function is converted toItem Example.

Test execution process

1. Test item preparation.

   • Before the test starts, theSession.perform_setup method to do some preprocessing.
   • This phase may include setting environment variables, initializing database connections, etc.

2. Test item implementation.

   • Methods control the actual execution of test items.
   • For eachItem instances, both of which call theSession.perform_test method to execute the test.

3. Collection of test results.

   • The results of the test execution are collected and stored in theItem Example.
   • May be triggeredpytest_runtest_logreport hook, which is used to process the test reports.

4. Exception Handling.

   • If an exception occurs during testing, thepytest will catch these exceptions and log them.
   • Exceptions can be passed through thepytest_runtest_makereport hook to handle it.

Test Report Generation

1. Session instance is responsible for collecting all test results.
2. attribute will determine the exit status code of the program based on the test results.
3. pytest Reports can be generated in a variety of formats, depending on the plug-in installed.

Sample Code Snippet

Here are some sample code snippets that show how thepytest Key parts of the source code:

# pytest/
def main(args=None):
    # Parsing command line arguments
    config = get_config(args)
    # Loading Plug-ins
    pm = PluginManager()
    pm.load_setuptools_entrypoints('pytest11')
    # Creating a Session Instance
    session = Session.from_parent(config, plugins=pm)
    # execute a test
    ()
    # Return to Exit Status
    return 

# pytest/
def perform_collect(session, collector):
    # Collecting test files and test functions
    items = []
    for item in ():
        (item)
    return items

# pytest/
def runtest_protocol(item, nextitem):
    # Execution of test items
    report = ()
    if report is None:
        # Handling of anomalies
        report = ()
    # Processing of test reports
    ._hookmanager.hook.pytest_runtest_logreport(report=report)