Solidity Unit Testing plugin

The Solidity Unit Testing plugin allows you to write and run automated tests for your Solidity smart contracts to verify they work correctly before deployment.

It helps you generate test files, write test functions using a built-in assertion library (like Assert.equal, Assert.notEqual), and execute those tests in a separate environment to see pass/fail results.

Activating the Solidity unit testing plugin

To activate the plugin, go to the Plugin Manager, search «Unit Testing» and enable the «Solidity Unit Testing» plugin.

When the plugin loads, you’ll see a screen like this:

Directorio de prueba

When you load the plugin, you need to specify a directory where the plugin will load and store test files. By default, it’s a tests folder at the root of your Workspace.

Nota

The plugin will not automatically create directories. You must click «Create» to generate the specified folder structure.

After specifying the test folder, click the «Create» button. Alternatively, you can select an existing folder as the tests folder by typing «/» followed by the name of the folder.

Generating tests

The plugin can generate generic test files that contain information about developing tests for a contract. The name of the generic test file is determined by the currently active .sol file on the Main Panel. If there is no active file, a generic test file named, newFile_test.sol will be created.

Below is an example of a generic test file:

pragma solidity >=0.4.22 <0.8.0;
import "remix_tests.sol"; // this import is automatically injected by Remix.
import "remix_accounts.sol";
// Import here the file to test.

// File name has to end with '_test.sol', this file can contain more than one testSuite contracts
contract testSuite {

    /// 'beforeAll' runs before all other tests
    /// More special functions are: 'beforeEach', 'beforeAll', 'afterEach' & 'afterAll'
    function beforeAll() public {
        // Here should instantiate tested contract
        Assert.equal(uint(1), uint(1), "1 should be equal to 1");
    }

    function checkSuccess() public {
        // Use 'Assert' to test the contract,
        // See documentation: https://remix-ide.readthedocs.io/en/latest/assert_library.html
        Assert.equal(uint(2), uint(2), "2 should be equal to 2");
        Assert.notEqual(uint(2), uint(3), "2 should not be equal to 3");
    }

    function checkSuccess2() public pure returns (bool) {
        // Use the return value (true or false) to test the contract
        return true;
    }

    function checkFailure() public {
        Assert.equal(uint(1), uint(2), "1 is not equal to 2");
    }

    /// Custom Transaction Context
    /// See more: https://remix-ide.readthedocs.io/en/latest/unittesting.html#customization
    /// #sender: account-1
    /// #value: 100
    function checkSenderAndValue() public payable {
        // account index varies 0-9, value is in wei
        Assert.equal(msg.sender, TestsAccounts.getAccount(1), "Invalid sender");
        Assert.equal(msg.value, 100, "Invalid value");
    }
}

Writing tests

Escriba suficientes pruebas unitarias para asegurarse de que su contrato funciona como se espera en diferentes escenarios.

Remix injects a built-in assert library for testing. You can visit the library documentation here.

Additionally, Remix allows the usage of special functions in the test file to make testing more structural. They are:

• beforeEach() - Se ejecuta antes de cada prueba

• beforeAll() - Se ejecuta antes de todas las pruebas

• afterEach() - Se ejecuta después de cada prueba

• afterAll() - Se ejecuta después de todas las pruebas

To get started, see this simple example.

Truco

You can use RemixAI to generate tests for your files.

Running tests

Once you are done with writing tests, select the file(s) and click on Run to execute the tests. The execution will run in a separate environment. After completing the execution of one file, a test summary will be shown:

En el caso de las pruebas fallidas, habrá más detalles de las afirmaciones para analizar el problema. Al hacer clic en la prueba fallida se resaltará la línea de código correspondiente en el editor.

Stopping tests

Si ha seleccionado varios archivos para ejecutar las pruebas y desea detener la ejecución, pulse el botón Stop. Detendrá la ejecución después de ejecutar las pruebas para el archivo actual.

Customizing tests

Remix facilita a los usuarios varios tipos de personalizaciones para probar un contrato correctamente.

1. Custom Compiler Context

Solidity Unit Testing refers to the Solidity Compiler plugin for compiler configurations. Configure Compiler, EVM Version, Enable Optimization & runs in the Solidity Compiler plugin and this will be used in the Solidity Unit Testing plugin for contract compilation before running unit tests.

2. Custom Transaction Context

For interacting with a contract’s method, the main parameters of a transaction are from address, value & gas. Typically, a method’s behaviour is tested with different values of these parameters.

Se pueden introducir valores personalizados para msg.sender & msg.value de transacción utilizando comentarios NatSpec, como:

/// #sender: account-0
/// #value: 10
function checkSenderIs0AndValueis10 () public payable {
    Assert.equal(msg.sender, TestsAccounts.getAccount(0), "wrong sender in checkSenderIs0AndValueis10");
    Assert.equal(msg.value, 10, "wrong value in checkSenderIs0AndValueis10");
}

Instructions to use:

1. Los parámetros deben definirse en el NatSpec del método

2. Cada clave de parámetro debe ir precedida de una almohadilla (#) y terminar con dos puntos después de un espacio (: ) como #sender: & #value:

3. Por ahora, la personalización sólo está disponible para los parámetros sender & value.

4. El remitente es la dirección from de una transacción a la que se accede utilizando msg.sender dentro de un método de contrato. Debe definirse en un formato fijo como `cuenta-<account_index>”

5. <account_index> varía de 0-2 antes del lanzamiento de remix-ide v0.10.0 y 0-9 después

6. remix_accounts.sol must be imported in your test file to use custom sender

7. El valor es el valor enviado junto con una transacción en wei al que se accede utilizando msg.value dentro de un método de contrato. Debe ser un número.

Regarding gas, Remix estimates the required gas for each transaction internally. Still if a contract deployment fails with Out-of-Gas error, it tries to redeploy it by doubling the gas. Deployment failing with double gas will show error: contract deployment failed after trying twice: The contract code couldn't be stored, please check your gas limit

Various test examples can be seen in examples section.

Puntos a recordar

• Un contrato de prueba no puede tener un método con parámetros. Tener un método de este tipo mostrará el error: Method 'methodname' can not have parameters inside a test contract.

• El número de cuentas de prueba es 3 antes del lanzamiento de remix-ide v0.10.0 y 10 después

• While a test file which imports remix_accounts.sol might not compile successfully with Solidity Compiler plugin, do not worry, this will have no bearing on its success with Solidity Unit Testing plugin.