Enhancing Foundry Testing Disabling Specific Tests By Contract And Test Name

by Sharif Sakr 77 views

Hey guys! Today, let's dive into a feature request for Foundry that aims to give us more granular control over disabling tests. This is especially useful when dealing with complex test suites where certain tests might need to be skipped based on specific contract and test name combinations. Let's break down the problem, explore the proposed solution, and see how it can make our testing workflows smoother.

The Challenge Fine-Grained Test Disabling

Currently, Foundry provides powerful match and nomatch options to disable tests by path, contract, or test name patterns. This is great for broad strokes, but what if you need to disable very specific tests? Imagine a scenario where you want to disable test A in Contract X but still run test B, while in Contract Y, you want to run test A but disable test B. The existing tools don't quite offer this level of precision. Imagine you have a suite of tests and need to skip tests based on combinations like [ (ContractX, TestA), (ContractY, TestB) ]. This kind of targeted control is what we're after.

To illustrate this, consider a practical example. We'll set up a scenario with a Counter contract and a test library to demonstrate the need for this feature. Understanding the need for fine-grained test control is the first step. Currently, Foundry's match and nomatch options provide ways to disable tests based on patterns in the path, contract, or test name. This is quite useful for broad strokes, such as disabling all tests in a specific contract or all tests with a certain name prefix. However, this approach falls short when we need more granular control. For instance, consider a scenario where you want to disable testA in ContractX but still run testB, while in ContractY, you want to run testA but disable testB. This level of precision is not achievable with the existing tools. The core issue is the need to target specific tests identified by a combination of the contract and test name. The goal is to have a mechanism that allows us to skip a list of tests, each identified by its unique contract and test name pairing. This would enable developers to tailor their test runs more precisely, focusing on the relevant aspects of their contracts while excluding known failing or irrelevant tests. Moreover, the current setup doesn't allow for configuring these skips programmatically from within a test contract. This limits the flexibility of test setups, especially when dealing with tests that depend on certain conditions or states of the contract.

Example Scenario Setting Up the Counter Project

Let’s start with a simple Counter project. We'll add a test library (TestLibrary.sol) that defines a set of general tests applicable to various contract functions. This library will include tests for both positive and negative outcomes, such as tests that expect a function to succeed and tests that expect it to revert. This setup is intentional to create scenarios where we need to selectively disable tests based on the specific behavior of different contract functions. We will then create two test contracts, IncrementTest.t.sol and SetNumberTest.t.sol, each inheriting from the TestLibrary. These contracts will apply the general tests from the library to specific functions of the Counter contract, namely increment() and setNumber(). This inheritance model is a powerful way to ensure consistent testing across different functions, but it also highlights the need for selective test disabling. For example, a test that checks for successful execution might be relevant for increment() but not for setNumber() under certain conditions, and vice versa. The intended workflow is as follows. First, for a new contract, a test file is added for each function, inheriting from the general TestLibrary. Then, the tests are run to check whether the passes and fails align with the expected behavior. Finally, in each t.sol file, for each property being tested, the specific versions of the complementary tests that should be skipped in the future are specified.

// file lib/TestLibrary.sol
import {Test} from "lib/forge-std/src/Test.sol";
abstract contract TestLibrary is Test {
    function doCall() internal virtual;
    function test_reverts() public {
        vm.expectRevert();
        doCall();
    }
    function test_succeeds() public {
        doCall();
    }
}

// file test/IncrementTest.t.sol
import {Counter} from "src/Counter.sol";
import {TestLibrary} from "lib/TestLibrary.sol";

contract IncrementTest is TestLibrary {
    Counter C = new Counter();
    function doCall() internal override {
        C.increment();
    }
}

// file test/SetNumberTest.t.sol
import {Counter} from "src/Counter.sol";
import {TestLibrary} from "lib/TestLibrary.sol";

contract SetNumberTest is TestLibrary {
    Counter C = new Counter();
    function doCall() internal override {
        C.setNumber(42);
    }
}

In this setup, TestLibrary.sol defines an abstract contract with a general set of tests, including test_reverts() and test_succeeds(). The IncrementTest.t.sol and SetNumberTest.t.sol contracts inherit these tests and apply them to the increment() and setNumber(42) functions of the Counter contract, respectively.

The Problem in Detail

TestLibrary.sol serves as a general, expandable list of tests, with each property being tested both positively and negatively. For complementary tests like these, at least one of the tests will generally fail. SetNumberTest.t.sol and Increment.t.sol both inherit the tests and apply them to a specific function of Counter.sol. The intended workflow is as follows:

  1. For a new contract, add a test file for each function that inherits the general Library.
  2. Run the tests and check whether the passes/fails are ok.
  3. In each t.sol file, specify for each property, which version of the complementary tests should be skipped in the future. (In the example, only one property is tested by the library, with a positive and a negative test.)

Step 3 is where the current challenge lies. The Counter example might be misleading because, for both functions, the same test might need to be disabled, which can still be done with the match/nomatch options. However, suppose that setNumber(42) reverts, and correctly so. In that case, we would ideally like to disable test_succeeds in SetNumberTest and test_reverts in IncrementTest. This level of granularity is not easily achievable with the current Foundry features.

The Proposed Solution Skip Cheatcode

To address this, the feature request suggests a new skip cheatcode. Imagine being able to tell Foundry to skip the current test, reporting it neither as PASS nor FAIL. This would allow for fine-grained control within the test contracts themselves. The idea is that each test could start with a conditional check: if (flag_for_this_test not set) vm.skip();. The flags could then be set in the .t.sol file, allowing you to control which tests are skipped based on the specific context.

Another approach could be a cheatcode that lets .t.sol files specify a list of tests within that file to include or exclude. This would provide a more declarative way to manage test skipping, making it easier to see at a glance which tests are being skipped and why.

Implementing a skip Cheatcode

One of the proposed solutions is to introduce a skip cheatcode. This cheatcode would instruct Foundry to skip the current test, without marking it as either a PASS or a FAIL. This is particularly useful in scenarios where a test's relevance depends on specific conditions or states of the contract. The implementation could involve adding a conditional check at the beginning of each test function: if (flag_for_this_test not set) vm.skip();. The flag_for_this_test would be a variable or a set of conditions defined within the .t.sol file. This approach allows for dynamic test skipping based on the context of the test execution. For example, if a particular function is expected to revert under certain conditions, the corresponding test_succeeds test could be skipped, and vice versa. This level of control ensures that only relevant tests are executed, providing a clearer picture of the contract's behavior. Moreover, this method enables developers to document the reasons for skipping tests directly within the test code, enhancing the maintainability and understandability of the test suite. Another potential approach is to introduce a cheatcode that allows .t.sol files to specify a list of tests within that file to include or exclude. This would provide a more declarative way to manage test skipping. Instead of embedding conditional checks within each test function, the test file could define a list of tests to be skipped. This method simplifies the test code and makes it easier to see at a glance which tests are being skipped and why.

Practical Example

Consider the Counter example again. Suppose that setNumber(42) reverts, as it should. We would then want to disable test_succeeds in SetNumberTest and test_reverts in IncrementTest. With a skip cheatcode, we could achieve this by setting flags in the respective .t.sol files:

// In SetNumberTest.t.sol
function test_succeeds() public {
    if (skipSetNumberTestSucceeds) vm.skip();
    // ... rest of the test
}

// In IncrementTest.t.sol
function test_reverts() public {
    if (skipIncrementTestReverts) vm.skip();
    // ... rest of the test
}

This way, we can precisely control which tests are run based on the specific behavior of each function in the Counter contract. This level of control is invaluable for maintaining a clean and efficient test suite.

Benefits and Use Cases

This feature would significantly enhance Foundry's testing capabilities, offering several key benefits:

  • Granular Control: Disable specific tests based on contract and test name combinations.
  • Dynamic Test Skipping: Skip tests based on conditions within the test contract.
  • Improved Test Suite Clarity: Focus on relevant tests, reducing noise from known failures.
  • Enhanced Workflow: Streamline the development process by allowing targeted testing.

Consider a scenario where you are working on a large project with multiple contracts and complex interactions. Some tests might be temporarily irrelevant due to ongoing development or known issues. Being able to selectively disable these tests allows you to focus on the parts of the system that are currently under development or require immediate attention. This targeted approach not only saves time but also reduces the cognitive load of dealing with a large number of failing tests that are not directly related to the task at hand. Another use case arises in upgradeable contracts. During an upgrade, certain tests from the previous version might not be applicable or might even fail due to the changes introduced in the new version. The ability to skip these tests temporarily while focusing on the tests relevant to the new version is crucial. Once the upgrade is complete and the new functionality is verified, the skipped tests can be revisited and updated or re-enabled as necessary. This ensures a smooth transition between versions and helps maintain the integrity of the test suite. Moreover, this feature can be particularly beneficial in continuous integration (CI) environments. In a CI pipeline, tests are run automatically to ensure that new changes do not break existing functionality. If certain tests are known to be failing due to external dependencies or temporary issues, skipping them in the CI pipeline can prevent false alarms and allow the team to focus on real issues. The skipped tests can be revisited and re-enabled once the underlying issues are resolved. This approach ensures that the CI pipeline remains reliable and provides timely feedback on the status of the codebase.

Use Cases in Complex Projects

In complex projects, this feature would be incredibly valuable. For instance, imagine a system with upgradeable contracts. During an upgrade, some tests from the previous version might not be relevant or might even fail. Being able to skip these tests temporarily while focusing on the new version's tests is crucial. Similarly, in a CI/CD pipeline, certain tests might be known to fail due to external dependencies or temporary issues. Skipping them in the pipeline prevents false alarms and allows the team to focus on real problems. These scenarios highlight the flexibility and efficiency gains that fine-grained test disabling can provide.

Conclusion

The ability to disable specific tests by contract and test name is a powerful addition to Foundry. The proposed skip cheatcode or a similar mechanism would give developers the control they need to manage complex test suites effectively. By implementing this feature, Foundry can become even more versatile and user-friendly, making our lives as smart contract developers a whole lot easier. What do you guys think? Let's discuss in the comments!