What does Arrange, Act, and Assert mean with respect to unit tests?

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TL/DR

Arrange, Act, and Assert describe the ideal structure for a unit test.

Firstly, you have to arrange all the necessary inputsand preconditions. Secondly, you perform some action or operation on the object to be tested.And finally, you assert that the expected outcome has occurred.

Here’s an example:

class EmailValidationTests: XCTestCase {
    func testValidEmail() {
        // Arrange
        let testEmail = "aryaman@digitalbunker.dev"
        
        // Act
        let isValidEmail =EmailValidation.validate(testEmail)

        // Assert
        XCTAssertTrue(isValidEmail)
    }

    func testInvalidEmail() {
        // Arrange
        let testEmail = "aryaman@digitalbunker"

        // Act
        let isValidEmail =EmailValidation.validate(testEmail)

        // Assert
        XCTAssertFalse(isValidEmail)
    }
}

This approach helps improve the readability of your tests and makes the expected behavior obvious.