User Guide

Platform detection

It’s very common to have one set of logic for Windows and another for all non-Windows (Unix-based) platforms, and PySys has a dedicated constant pysys.constants.IS_WINDOWS for that:

self.startProcess('cmd.exe' if IS_WINDOWS else 'bash', ...)

For finer grained platform detection we recommend using the facilities built into Python, for example platform.uname() and platform.platform().

Skipping tests

If your run.py logic detects that a test should not be executed for this platform or mode, simply use self.skipTest(...) near the top of the test’s execute() method, specifying the reason for the skip:

self.skipTest('MyFeature is not supported on Windows')

As well as setting the test outcome and reason, this will raise an exception ensuring that the rest of execute() and validate() do not get executed.

Alternatively if the test should be skipped regardless of platform/mode etc, it is best to specify that statically in your pysystest.xml file:

<skipped reason="Skipped until bug #12345 is fixed"/>

Checking for error messages in log files

The BaseTest.assertGrep() method is an easy way to check that there are no error messages in log files from processes started by PySys. Rather than checking for an expression such as ' ERROR: ', it is recommended to define your expression so that the error message itself is included, e.g.:

self.assertGrep('myprocess.log', expr=' ERROR: .*', contains=False)

This approach ensures that the error message itself is included in the test’s console output, run.log and the summary of failed test outcomes, which avoids the need to open up the individual logs to find out what happened, and makes it much easier to triage test failures, especially if several tests fail for the same reason.

Sharing logic for validation across tests

Often you may have some standard logic that needs to be used in the validation of many/all testcases, such as checking log files for errors.

One recommended pattern for this is to define a helper function in a custom BaseTest subclassed by all your tests that is named after what is being checked - for example checkLogsForErrors() - and explicitly call that method from the BaseTest.validate() method of each test. That approach allows you to later customize the logic by changing just one single place, and also to omit it for specific tests where it is not wanted.

Configuring and overriding test options

PySys provides two mechanisms for specifying options such as credentials, hostnames, or test duration/iteration that you might want to change or override when running tests:

  • Testcase attributes, which are just variables on the Python testcase instance (or a BaseTest subclass shared by many tests). Attributes can be overridden on the command line when executing pysys run.

    Attributes are useful for settings specific to an individual testcase such as the number of iterations or time duration to use for a performance test. A user running the test locally you might want to temporarily set to a lower iteration count while getting the test right, or perhaps try a higher value to get a more stable performance result.

  • Project properties. The default value is specified in the pysysproject.xml file or in a .properties file referenced from it.

    Properties can be overridden using an environment variable. Project properties are useful for things like credentials and hostnames that are shared across many testcases, and where you might want to set up customizations in your shell so that you don’t need to keep specifying them every time you invoke pysys run.

To use a testcase attribute, set the default value on your test or basetest before BaseTest.__init__() is called. The easiest way to do this in an individual testcase is usually to use a static attribute on the test class, for example:

class PySysTest(BaseTest):

        myIterationCount = 100*1000 # can be overridden with -XmyIterationCount=

        def execute(self):
                self.log.info('Using iterations=%d', self.myIterationCount)
                ...

If instead of setting a default for just one test you wish to set the default for many tests from your custom BaseTest subclass, then you would do the same thing in the definition of your BaseTest subclass.

Once the default value is defined with a static attribute, you can override the value when you run your test using the -X option:

pysys run -XmyIterationCount=10

If the attribute was defined with a default value of int, float or bool then the -X value will be automatically converted to that type; otherwise, it will be a string.

The other mechanism that PySys supports for configurable test options is project properties.

To use a project property that can be overridden with an environment variable, add a property element to your pysysproject.xml file:

<property name="myCredentials" value="${env.MYCOMPANY_CREDENTIALS}" default="testuser:testpassword"/>

This property can will take the value of the specified environment variable, or else the default if not set.

Another way to specify default project property values is to put them into a Java-style .properties file. You can use properties to specify which file is loaded, so it would be possible to customize using environment variables:

<property name="myProjectPropertiesFile" value="${env.MYCOMPANY_CUSTOM_PROJECT_PROPERTIES}" default="${testRootDir}/default-config.properties"/>
<property file="${myProjectPropertiesFile}"/>

To use projects properties in your testcase, just access the attributes on self.project from either a test instance or a runner:

def execute(self):
        self.log.info('Using username=%s and password %s' % self.project.myCredentials.split(':'))

Property properties will always be of string type.

Producing code coverage reports

PySys can be extended to produce code coverage reports for any language.

Built-in support is provided for producing coverage reports for programs written in Python, using the coverage.py library. To enable this, set the pythonCoverageDir and collect-test-output project options (see below), make sure you’re using BaseTest.startPython to execute Python from within your tests, and run PySys with -XpythonCoverage=true.

If you wish to produce coverage reports using any other tool or language (such as Java), this is easy to achieve by following the same pattern:

  • When your tests start the program(s) whose coverage is to be measured, add the required arguments or environment variables to enable coverage using the coverage tool of your choice.

    For example, for Python programs PySys does this by adding -m coverage run to the command line of Python programs started using the BaseTest.startPython method (and setting COVERAGE_FILE to a unique filename in the test output directory), when the pythonCoverage property is set to true (typically by pysys.py run -X pythonCoverage=true). The pythonCoverageArgs project property can be set to provide customized arguments to the coverage tool, such as which files to include/exclude, or a --rcfile= specifying a coverage configuration file.

  • Configure your pysysproject.xml to collect the coverage files generated in your testcase output directories and put them into a single directory. Add a project property to specify the directory location so it can be located by the code that will generate the report. For Python programs, you’d configure PySys to do it like this:

    <property name="pythonCoverageDir" value="coverage-python-@OUTDIR@"/>
<collect-test-output pattern=".coverage*" outputDir="${pythonCoverageDir}" outputPattern="@FILENAME@_@TESTID@_@UNIQUE@"/>

    Note that collect-test-output will delete the specified outputDir each time PySys runs some tests. If you wish to preserve output from previous runs, you could add a property such as ${startDate}_${startTime} to the directory name to make it unique each time.

    In addition to any standard ${...} property variables from the project configuration, the output pattern can contain these three @...@ substitutions which are specific to the collect-test-output outputPattern:

    • @FILENAME@ is the original base filename, to which you can add prefixes or suffixes as desired.

    • @TESTID@ is replaced by the identifier of the test that generated the output file, which may be useful for tracking where each one came from.

    • @UNIQUE@ is replaced by a number that ensures the file does not clash with any other collected output file from another test. The @UNIQUE@ substitution variable is mandatory.

  • Add a custom runner class, and provide a pysys.baserunner.BaseRunner.processCoverageData() implementation that combines the coverage files from the directory where they were collected and generates any required reports. The default implementation already does this for Python programs. Note that when reading the property value specifying the output directory any ${...} property values will be substituted automatically, but any @...@ values such as @OUTDIR@ must be replaced manually (since the value of runner.outsubdir is not available when the project properties are resolved).

  • Add a custom BaseTest class to be inherited by all your tests and from BaseTest.setup method set self.disableCoverage=True for test groups that should not use coverage, such as performance tests. For example:

    if 'performance' in self.descriptor.groups: self.disableCoverage = True

  • If using a continuous integration system or centralized code coverage database, you could optionally upload the coverage data there from the directory PySys collected it into, so there is a permanent record of any changes in coverage over time.

Running tests in multiple modes

One of the most powerful features of PySys is the ability to run the same test in multiple modes from a single execution. This could be useful for cases such as a web test that needs to pass against multiple supported web browsers, or a set of tests that should be run against various different database but can also be run against a mocked database for quick local development.

Using modes is fairly straightforward. First make sure your project configuration includes:

<property name="supportMultipleModesPerRun" value="true"/>

If you created your project using PySys 1.4.1 or later this will already be present. Next you should edit the pysystest.xml files for tests that need to run in multiple modes, and add a list of the supported modes:

<classification>
     <groups>...</groups>
     <modes inherit="true">
             <mode>MockDatabase_Firefox</mode>
             <mode>MyDatabase2.0_Chrome</mode>
     </modes>
</classification>

When naming modes, TitleCase is recommended, and dot and underscore characters may be used; typically dot is useful for version numbers and underscore is useful for separating out different dimensions e.g. database vs web browser as in the above example. PySys will give an error if you use different capitalization for the same mode in different places, as this would likely result in test bugs.

The first mode listed is designated the “primary” mode which means it’s the one that is used by default when running your tests without a --mode argument. It’s best to choose either the fastest mode or else the one that is most likely to show up interesting issues as the primary mode.

In large projects you may wish to configure modes in a pysysdirconfig.xml file in a parent directory rather than in pysystest.xml, which will by default be inherited by all nested testcases (unless inherit="false" is specified in the <modes> element), and so there’s a single place to edit the modes list if you need to change them later. It’s also possible to create a custom DescriptorLoader subclass that dynamically adds modes from Python code, perhaps based on the groups specified in each descriptor or runtime information such as the current operating system.

You can find the mode that this test is running in using self.mode. To ensure typos and inconsistencies in individual test descriptor modes do no go unnoticed, it is best to provide constants for the possible mode values and/or do validation and unpacking of modes in the BaseTest.setup method of a custom BaseTest class like this:

class MyBaseTest(BaseTest):
        def setup(self):
                super(MyBaseTest, self).setup()

                # Unpack and validate mode
                self.databaseMode, self.browserMode = self.mode.split('_')
                assert self.browserMode in ['Chrome', 'Firefox'], self.browserMode

                # This is a convenient pattern for specifying the method or class
                # constructor to call for each mode, and to get an exception if an
                # invalid mode is specified
                dbHelperFactory = {
                        'MockDatabase': MockDB,
                        'MyDatabase2.0': lambda: self.startMyDatabase('2.0')
                }[self.databaseMode]
                ...
                # Call the supplied method to start/configure the database
                self.db = dbHelperFactory()

Finally, PySys provides a rich variety of pysys run arguments to control which modes your tests will run with. By default it will run every test in its primary mode (for tests with no mode, the primary mode is self.mode==None) - which is great for quick checks during development of your application and testcases.

Your main test run (perhaps in a CI job) probably wants to run tests in all modes:

pysys run --mode ALL --threads auto

You can also specify specifies modes to run in, or to run everything except specified modes:

pysys run --mode MyMode1,MyMode2
pysys run --mode !MyMode3,!MyMode4

After successfully getting all your tests passing in their primary mode, it could be useful to run them in every mode other than the primary one:

pysys run --mode !PRIMARY

For reporting purposes, all testcases must have a unique id. With a multiple mode test this is achieved by having the id automatically include a ~Mode suffix. If you are reporting performance results from a multi-mode test, make sure you include the mode in the resultKey when you all BaseTest.reportPerformanceResult, since the resultKey must be globally unique.

In addition to the --mode argument which affects all selected tests, it is possible to run a specific test in a specific mode. This can be useful when you have a few miscellaneous test failures and just want to re-run the failing tests:

pysys run MyTest_001~MockDatabase MyTest_020~MyDatabase_2.0

Test ids and structuring large projects

Each test has a unique id which is used in various places such as when reporting passed/failed outcomes. By default the id is just the name of the directory containing the pysystest.xml file.

You can choose a suitable naming convention for your tests. For example, you might wish to differentiate with just a numeric suffix such as:

MyApp_001
MyApp_002
MyApp_003

This has the benefit that it’s easy to refer to tests when communicating with other developers, and that you can run tests on the command line by specifying just a number, but you have to look at the test title to discover what it does.

Alternatively you could choose to use a semantically meaningful name for each test:

MyApp_TimeoutValueWorks
MyApp_TimeoutInvalidValuesAreRejected
MyApp_ValidCredentialsAreAccepted

These test ids are easier to understand but can’t be referred to as concisely.

Whatever scheme you use for naming test ids, if you have a large set of tests you will want to separate them out into different directories, so that related tests can be executed and maintained together. You might have different directories for different subsystems/parts of your application, and/or for different kinds of testing:

/  (root dir containing pysysproject.xml)

/SubSystem1/unit/
/SubSystem1/correctness/
/SubSystem1/long-running/
/SubSystem1/performance/

/SubSystem2/unit/
/SubSystem2/correctness/
/SubSystem2/long-running/
/SubSystem2/performance/
etc.

It is important to ensure every test has a unique id. Although it would be possible to do this by convention in the individual test directory names, this is fragile and could lead to clashes if someone forgets. Therefore for large projects it is usually best to add a pysysdirconfig.xml file to provide default configuration for each directory of testcases.

For example, in SubSystem1/performance you could create a pysysdirconfig.xml file containing:

<?xml version="1.0" encoding="utf-8"?>
<pysysdirconfig>
  <id-prefix>SubSystem1_perf.</id-prefix>

  <classification>
        <groups inherit="true">
          <group>subsystem1</group>
          <group>performance</group>
        </groups>

        <modes inherit="true">
        </modes>

  </classification>

  <execution-order hint="-100.0"/>

  <!-- Uncomment this to mark all tests under this directory as skipped
        (overrides the state= attribute on individual tests). -->
  <!-- <skipped reason=""/> -->

</pysysdirconfig>

This serves several useful purposes:

  • It adds a prefix “SubSystem1_perf.” to the beginning of the test directory names to ensure there’s a unique id for each one with no chance of conflicts across different directories.

  • It adds groups that make it possible to run all your performance tests, or all your tests for a particular part of the application, in a single command.

  • It specifies that the performance tests will be run with a lower priority, so they execute after more urgent (and quicker) tests such as unit tests.

  • It provides the ability to temporarily skip a set of tests if they are broken temporarily pending a bug fix.

By default both modes and groups are inherited from pysysdirconfig.xml files in parent directories, but inheriting can be disabled in an individual descriptor by setting inherit="false", in case you have a few tests that only make sense in one mode. Alternatively, you could allow the tests to exist in all modes but call self.skipTest <BaseTest.skipTest> at the start of the test BaseTest.execute method if the test cannot execute in the current mode.

See the pysysdirconfig.xml sample in pysys/xml/templates/dirconfig for a full example of a directory configuration file.

Controlling execution order

In large projects where the test run takes several hours or days, you may wish to control the order that PySys executes different groups of tests - or tests with different modes, to maximize the chance of finding out quickly if something has gone wrong, and perhaps to prioritize running fast unit and correctness tests before commencing on longer running performance or soak tests.

By default, PySys runs tests based on the sorting them by the full path of the pysystest.xml files. If you have tests with multiple modes, PySys will run all tests in their primary mode first, then any/all tests which list a second mode, followed by 3rd, 4th, etc.

All of this can be customized using the concept of an execution order hint. Every test descriptor is assigned an execution order hint, which is a positive or negative floating point number which defaults to 0.0, and is used to sort the descriptors before execution. Higher execution order hints mean later execution. If two tests have the same hint, PySys falls back on using the path of the pysystest.xml file to determine a canonical order.

The hint for each test is generated by adding together hint components from the following:

  • A test-specific hint from the pysystest.xml file’s <execution-order hint="..."/>. If the hint is blank (the default), the test inherits any hint specified in a pysysdirconfig.xml file in an ancestor folder, or 0.0 if there aren’t any. Note that hints from pysysdirconfig.xml files are not added together; instead, the most specific wins.

  • All <execution-order> elements in the project configuration file which match the mode and/or group of the test. The project configuration is the place to put mode-specific execution order hints, such as putting a particular database or web browser mode earlier/later. See the sample pysysproject.xml file for details.

  • For multi-mode tests, the secondaryModesHintDelta specified in the project configuration (unless it’s set to zero), multiplied by a number indicating which mode this is. If a test had 3 modes Mode1, Mode2 and Mode3 then the primary mode (Mode1) would get no additional hint, Mode2 would get secondaryModesHintDelta added to its hint and Mode3 would get 2 x secondaryModesHintDelta added to its hint. This is the mechanism PySys uses to ensure all tests run first in their primary mode before any tests run in their secondary modes. Usually the default value of secondaryModesHintDelta = +100.0 is useful and avoids the need for too much mode-specific hint configuration (see above). However if you prefer to turn it off to have more manual control - or you prefer each test to run in all modes before moving on to the next test - then simply set secondaryModesHintDelta to 0.

For really advanced cases, you can programmatically set the executionOrderHint on each descriptor by providing a custom pysys.xml.descriptor.DescriptorLoader or in the constructor of a custom pysys.baserunner.BaseRunner class.