Unit tests in Laravel - Step-by-Step Execution

Concept Flow - Unit tests

Write Test Method

↓

Test Setup

↓

Run PHPUnit

↓

Execute Test Code

↓

Assert Expected Result

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Pass or Fail

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Fix Code or Test

↩Back to Write Test Method

Unit tests in Laravel follow a cycle: write a test method, setup environment, run it, execute code, check results, then fix code or tests based on pass/fail.

Execution Sample

Laravel

public function testAddition()
{
    $sum = 2 + 3;
    $this->assertEquals(5, $sum);
}

This test checks if adding 2 and 3 equals 5 using Laravel's PHPUnit test method.

Execution Table

Step	Action	Code Evaluated	Result	Test Outcome
1	Start testAddition method	public function testAddition()	Method ready to run	N/A
2	Calculate sum	$sum = 2 + 3;	$sum = 5	N/A
3	Assert equals	$this->assertEquals(5, $sum);	5 equals 5	Pass
4	Test ends	Method completes	No errors	Pass

💡 Test ends after assertion passes confirming 2 + 3 equals 5

Variable Tracker

Variable	Start	After Step 2	Final
$sum	undefined	5	5

Key Moments - 2 Insights

Why does the test fail if the expected value in assertEquals is wrong?

Because assertEquals compares the expected value with the actual result. If they differ, the test fails as shown in step 3 of the execution_table.

What happens if the test method name does not start with 'test'?

PHPUnit will not recognize or run the method as a test, so no test execution or assertion happens.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of $sum after step 2?

A 3

B 2

C 5

D undefined

💡 Hint

Check the 'Result' column in row 2 of execution_table

At which step does the test check if the result is correct?

A Step 2

B Step 3

C Step 1

D Step 4

💡 Hint

Look for the 'Assert equals' action in execution_table

If the assertion expected 6 instead of 5, what would happen at step 3?

A Test fails

B Test passes

C Test skips assertion

D Test crashes

💡 Hint

assertEquals compares expected and actual values; mismatch causes failure

Concept Snapshot

Unit tests in Laravel use PHPUnit.
Write test methods starting with 'test'.
Use assertions like assertEquals(expected, actual).
Run tests with php artisan test.
Tests pass if assertions match, fail otherwise.

Full Transcript

Unit tests in Laravel are small pieces of code that check if parts of your app work correctly. You write a test method starting with 'test'. Inside, you run some code and then check the result using assertions like assertEquals. When you run tests, Laravel uses PHPUnit to execute these methods. If the actual result matches the expected, the test passes. If not, it fails and you fix your code or test. This cycle helps keep your app reliable.

Practice

1. What is the main purpose of unit tests in Laravel?

easy

A. To deploy the application to production

B. To create database migrations

C. To check small parts of code to catch errors early

D. To style the user interface

Solution

1. Step 1: Understand unit test purpose

   Unit tests focus on testing small, isolated parts of code to find bugs early.

2. Step 2: Compare options with unit test goals

   Only To check small parts of code to catch errors early describes this purpose; others relate to deployment, database, or UI.

3. Final Answer:

   To check small parts of code to catch errors early -> Option C

4. Quick Check:

   Unit tests = catch errors early [OK]

Hint: Unit tests check small code parts for bugs early [OK]

Common Mistakes:

• Confusing unit tests with deployment tasks
• Thinking unit tests handle UI styling
• Mixing unit tests with database migrations

2. Which of the following is the correct way to define a test method in a Laravel unit test class?

easy

A. function exampleTest() {}

B. public function testExample() {}

C. public test function example() {}

D. def test_example():

Solution

1. Step 1: Recall Laravel test method syntax

   Laravel test methods are public functions starting with 'test' or annotated with @test.

2. Step 2: Check each option's syntax

   public function testExample() {} uses 'public function testExample() {}' which is correct PHP and Laravel style. Others are invalid PHP or wrong syntax.

3. Final Answer:

   public function testExample() {} -> Option B

4. Quick Check:

   Test methods = public function testName() [OK]

Hint: Test methods start with 'test' and are public functions [OK]

Common Mistakes:

• Using wrong function visibility or missing 'public'
• Using Python syntax in PHP tests
• Incorrect function declaration order

3. Given this Laravel test method, what will be the test result?

public function testSum() {
    $a = 2;
    $b = 3;
    $this->assertEquals(5, $a + $b);
}

medium

A. Test throws a syntax error

B. Test fails because 2 + 3 does not equal 5

C. Test is skipped automatically

D. Test passes because 2 + 3 equals 5

Solution

1. Step 1: Evaluate the sum in the test

   Variables $a and $b are 2 and 3, so $a + $b equals 5.

2. Step 2: Check the assertion

   The assertion expects 5 and compares it to $a + $b, which is 5, so it matches and passes.

3. Final Answer:

   Test passes because 2 + 3 equals 5 -> Option D

4. Quick Check:

   2 + 3 = 5 passes assertion [OK]

Hint: Check math in assertEquals carefully [OK]

Common Mistakes:

• Assuming test fails without checking values
• Confusing assertEquals parameter order
• Thinking syntax error without code issues

4. Identify the error in this Laravel unit test method:

public function testUserName() {
    $user = new User();
    $user->name = 'Alice';
    $this->assertEquals('Alice', $user->username);
}

medium

A. Property 'username' does not exist on User model

B. Missing semicolon after new User()

C. assertEquals parameters are reversed

D. Test method name does not start with 'test'

Solution

1. Step 1: Check User model property usage

   The code sets $user->name but asserts $user->username, which likely does not exist.

2. Step 2: Verify syntax and method name

   There is a semicolon after new User(), and method name starts with 'test', so no syntax or naming errors.

3. Final Answer:

   Property 'username' does not exist on User model -> Option A

4. Quick Check:

   Assert property exists before testing [OK]

Hint: Check property names match exactly in tests [OK]

Common Mistakes:

• Assuming assertEquals parameters order causes error
• Overlooking property name mismatch
• Thinking method name is incorrect

5. You want to test a method that returns a list of active users from the database. Which approach best fits Laravel unit testing principles?

hard

A. Mock the User model's active() method and assert it returns expected data

B. Run the actual database query in the test without mocking

C. Test the method by printing results and checking manually

D. Skip testing because database queries are not testable

Solution

1. Step 1: Understand unit test scope

   Unit tests isolate code parts, so database calls should be mocked to avoid external dependencies.

2. Step 2: Evaluate options for best practice

   Mock the User model's active() method and assert it returns expected data mocks the User model's method and asserts expected results, fitting unit test principles. Run the actual database query in the test without mocking uses real DB, which is integration testing. Test the method by printing results and checking manually is manual and not automated. Skip testing because database queries are not testable is incorrect.

3. Final Answer:

   Mock the User model's active() method and assert it returns expected data -> Option A

4. Quick Check:

   Unit tests mock external calls [OK]

Hint: Mock external dependencies in unit tests [OK]

Common Mistakes:

• Running real database queries in unit tests
• Relying on manual output checks
• Skipping tests for database-related methods