Unit Test Framework Package

About

This package adds a unit test framework capable of building tests for multiple contexts including the UEFI shell environment and host-based environments. It allows for unit test development to focus on the tests and leave error logging, result formatting, context persistance, and test running to the framework. The unit test framework works well for low level unit tests as well as system level tests and fits easily in automation frameworks.

UnitTestLib

The main "framework" library. The core of the framework is the Framework object, which can have any number of test cases and test suites registered with it. The Framework object is also what drives test execution.

The Framework also provides helper macros and functions for checking test conditions and reporting errors. Status and error info will be logged into the test context. There are a number of Assert macros that make the unit test code friendly to view and easy to understand.

Finally, the Framework also supports logging strings during the test execution. This data is logged to the test context and will be available in the test reporting phase. This should be used for logging test details and helpful messages to resolve test failures.

UnitTestPersistenceLib

Persistence lib has the main job of saving and restoring test context to a storage medium so that for tests that require exiting the active process and then resuming state can be maintained. This is critical in supporting a system reboot in the middle of a test run.

UnitTestResultReportLib

Library provides function to run at the end of a framework test run and handles formatting the report. This is a common customization point and allows the unit test framework to fit its output reports into other test infrastructure. In this package a simple library instances has been supplied to output test results to the console as plain text.

Samples

There is a sample unit test provided as both an example of how to write a unit test and leverage many of the features of the framework. This sample can be found in the Test/UnitTest/Sample/SampleUnitTest directory.

The sample is provided in PEI, SMM, DXE, and UEFI App flavors. It also has a flavor for the HOST_APPLICATION build type, which can be run on a host system without needing a target.

Usage

This section is built a lot like a "Getting Started". We'll go through some of the components that are needed when constructing a unit test and some of the decisions that are made by the test writer. We'll also describe how to check for expected conditions in test cases and a bit of the logging characteristics.

Most of these examples will refer to the SampleUnitTestUefiShell app found in this package.

Requirements - INF

In our INF file, we'll need to bring in the UnitTestLib library. Conveniently, the interface header for the UnitTestLib is located in MdePkg, so you shouldn't need to depend on any other packages. As long as your DSC file knows where to find the lib implementation that you want to use, you should be good to go.

See this example in 'SampleUnitTestApp.inf'...

[Packages]
  MdePkg/MdePkg.dec

[LibraryClasses]
  UefiApplicationEntryPoint
  BaseLib
  DebugLib
  UnitTestLib
  PrintLib

Requirements - Code

Not to state the obvious, but let's make sure we have the following include before getting too far along...

#include <Library/UnitTestLib.h>

Now that we've got that squared away, let's look at our 'Main()'' routine (or DriverEntryPoint() or whatever).

Configuring the Framework

Everything in the UnitTestPkg framework is built around an object called -- conveniently -- the Framework. This Framework object will contain all the information about our test, the test suites and test cases associated with it, the current location within the test pass, and any results that have been recorded so far.

To get started with a test, we must first create a Framework instance. The function for this is InitUnitTestFramework. It takes in CHAR8 strings for the long name, short name, and test version. The long name and version strings are just for user presentation and relatively flexible. The short name will be used to name any cache files and/or test results, so should be a name that makes sense in that context. These strings are copied internally to the Framework, so using stack-allocated or literal strings is fine.

In the 'SampleUnitTestUefiShell' app, the module name is used as the short name, so the init looks like this.

DEBUG(( DEBUG_INFO, "%a v%a\n", UNIT_TEST_APP_NAME, UNIT_TEST_APP_VERSION ));

//
// Start setting up the test framework for running the tests.
//
Status = InitUnitTestFramework( &Framework, UNIT_TEST_APP_NAME, gEfiCallerBaseName, UNIT_TEST_APP_VERSION );

The &Framework returned here is the handle to the Framework. If it's successfully returned, we can start adding test suites and test cases.

Test suites exist purely to help organize test cases and to differentiate the results in reports. If you're writing a small unit test, you can conceivably put all test cases into a single suite. However, if you end up with 20+ test cases, it may be beneficial to organize them according to purpose. You must have at least one test suite, even if it's just a catch-all. The function to create a test suite is CreateUnitTestSuite. It takes in a handle to the Framework object, a CHAR8 string for the suite title and package name, and optional function pointers for a setup function and a teardown function.

The suite title is for user presentation. The package name is for xUnit type reporting and uses a '.'-separated hierarchical format (see 'SampleUnitTestApp' for example). If provided, the setup and teardown functions will be called once at the start of the suite (before any tests have run) and once at the end of the suite (after all tests have run), respectively. If either or both of these are unneeded, pass NULL. The function prototypes are UNIT_TEST_SUITE_SETUP and UNIT_TEST_SUITE_TEARDOWN.

Looking at 'SampleUnitTestUefiShell' app, you can see that the first test suite is created as below...

//
// Populate the SimpleMathTests Unit Test Suite.
//
Status = CreateUnitTestSuite( &SimpleMathTests, Fw, "Simple Math Tests", "Sample.Math", NULL, NULL );

This test suite has no setup or teardown functions. The &SimpleMathTests returned here is a handle to the suite and will be used when adding test cases.

Great! Now we've finished some of the cruft, red tape, and busy work. We're ready to add some tests. Adding a test to a test suite is accomplished with the -- you guessed it -- AddTestCase function. It takes in the suite handle; a CHAR8 string for the description and class name; a function pointer for the test case itself; additional, optional function pointers for prerequisite check and cleanup routines; and and optional pointer to a context structure.

Okay, that's a lot. Let's take it one piece at a time. The description and class name strings are very similar in usage to the suite title and package name strings in the test suites. The former is for user presentation and the latter is for xUnit parsing. The test case function pointer is what is actually executed as the "test" and the prototype should be UNIT_TEST_FUNCTION. The last three parameters require a little bit more explaining.

The prerequisite check function has a prototype of UNIT_TEST_PREREQUISITE and -- if provided -- will be called immediately before the test case. If this function returns any error, the test case will not be run and will be recorded as UNIT_TEST_ERROR_PREREQUISITE_NOT_MET. The cleanup function (prototype UNIT_TEST_CLEANUP) will be called immediately after the test case to provide an opportunity to reset any global state that may have been changed in the test case. In the event of a prerequisite failure, the cleanup function will also be skipped. If either of these functions is not needed, pass NULL.

The context pointer is entirely case-specific. It will be passed to the test case upon execution. One of the purposes of the context pointer is to allow test case reuse with different input data. (Another use is for testing that wraps around a system reboot, but that's beyond the scope of this guide.) The test case must know how to interpret the context pointer, so it could be a simple value, or it could be a complex structure. If unneeded, pass NULL.

In 'SampleUnitTestUefiShell' app, the first test case is added using the code below...

AddTestCase( SimpleMathTests, "Adding 1 to 1 should produce 2", "Addition", OnePlusOneShouldEqualTwo, NULL, NULL, NULL );

This test case calls the function OnePlusOneShouldEqualTwo and has no prerequisite, cleanup, or context.

Once all the suites and cases are added, it's time to run the Framework.

//
// Execute the tests.
//
Status = RunAllTestSuites( Framework );

A Simple Test Case

We'll take a look at the below test case from 'SampleUnitTestApp'...

UNIT_TEST_STATUS
EFIAPI
OnePlusOneShouldEqualTwo (
  IN UNIT_TEST_FRAMEWORK_HANDLE  Framework,
  IN UNIT_TEST_CONTEXT           Context
  )
{
  UINTN     A, B, C;

  A = 1;
  B = 1;
  C = A + B;

  UT_ASSERT_EQUAL(C, 2);
  return UNIT_TEST_PASSED;
} // OnePlusOneShouldEqualTwo()

The prototype for this function matches the UNIT_TEST_FUNCTION prototype. It takes in a handle to the Framework itself and the context pointer. The context pointer could be cast and interpreted as anything within this test case, which is why it's important to configure contexts carefully. The test case returns a value of UNIT_TEST_STATUS, which will be recorded in the Framework and reported at the end of all suites.

In this test case, the UT_ASSERT_EQUAL assertion is being used to establish that the business logic has functioned correctly. There are several assertion macros, and you are encouraged to use one that matches as closely to your intended test criterium as possible, because the logging is specific to the macro and more specific macros have more detailed logs. When in doubt, there are always UT_ASSERT_TRUE and UT_ASSERT_FALSE. Assertion macros that fail their test criterium will immediately return from the test case with UNIT_TEST_ERROR_TEST_FAILED and log an error string. Note that this early return can have implications for memory leakage.

At the end, if all test criteria pass, you should return UNIT_TEST_PASSED.

More Complex Cases

To write more advanced tests, first take a look at all the Assertion and Logging macros provided in the framework.

Beyond that, if you're writing host-based tests and want to take a dependency on the UnitTestFrameworkPkg, you can leverage the cmocka.h interface and write tests with all the features of the Cmocka framework.

Documentation for Cmocka can be found here: https://api.cmocka.org/

Development

When using the EDK2 Pytools for CI testing, the host-based unit tests will be built and run on any build that includes the NOOPT build target.

If you are trying to iterate on a single test, a convenient pattern is to build only that test module. For example, the following command will build only the SafeIntLib host-based test from the MdePkg...

stuart_ci_build -c .pytool/CISettings.py TOOL_CHAIN_TAG=VS2017 -p MdePkg -t NOOPT BUILDMODULE=MdePkg/Test/UnitTest/Library/BaseSafeIntLib/TestBaseSafeIntLib.inf

Known Limitations

PEI, DXE, SMM

While sample tests have been provided for these execution environments, only cursory build validation has been performed. Care has been taken while designing the frameworks to allow for execution during boot phases, but only UEFI Shell and host-based tests have been thoroughly evaluated. Full support for PEI, DXE, and SMM is forthcoming, but should be considered beta/staging for now.

Host-Based Support vs Other Tests

The host-based test framework is powered internally by the Cmocka framework. As such, it has abilities that the target-based tests don't (yet). It would be awesome if this meant that it was a super set of the target-based tests, and it worked just like the target-based tests but with more features. Unfortunately, this is not the case. While care has been taken to keep them as close a possible, there are a few known inconsistencies that we're still ironing out. For example, the logging messages in the target-based tests are cached internally and associated with the running test case. They can be saved later as part of the reporting lib. This isn't currently possible with host-based. Only the assertion failures are logged.

We will continue trying to make these as similar as possible.

Copyright © Microsoft Corporation. SPDX-License-Identifier: BSD-2-Clause-Patent