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In this lecture, we are going to write our first test to get started.

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We will update the test file for the app component in your editor.

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Search for this file in our project.

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Let's rename the file by changing the extension from spec broken to spec.

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Next, let's clear the contents of the file.

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The first test will be writing is called a sanity test.

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Similar to the development process of an application, you are bound to encounter errors while writing

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tests.

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You're going to spend time figuring out why a test isn't working.

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In some cases, a test may not fail because there's anything wrong with your code.

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The cause of a failure can come from your tool set.

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It's common for tools to fail.

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If a tool fails, we can safely assume there's nothing wrong with our code.

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That brings us to the question how do we verify a tool fails?

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The most common solution is to write a sanity test.

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A sanity test is a test that always passes.

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If a sanity test fails, we can assume there's something wrong with our tools.

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I highly recommend writing a sanity test as your first test.

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We're going to write a sanity test inside the app test file first at a function called Describe.

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The described function is defined by the Jasmyn Library.

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It's not uncommon for an application to have hundreds of tests.

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Organizing your tests is very important.

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It'll help you debug your application.

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The described function allows us to create a test suite, which is another way of saying a group of

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tests.

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This function has two arguments.

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The first argument is a description of the test suite.

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Typically, developers will write the name of the component.

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Let's set this argument to app component.

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The second argument is a function let's pass in an arrow function.

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Inside this function, we can begin defining our tests.

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Let's run a function called it.

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Immediately.

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You'll notice we're not importing these functions before using them.

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We're running our code through Jasmine by default.

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Jasmine will define a set of global functions.

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The IT function is predefined for us.

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We don't have to do anything to make sure it's available.

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The IT function allows us to write a single test.

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Initially, the name of the function might sound strange.

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However, throughout this section you're going to quickly discover that tests are verbose.

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Keep following along and you'll see what I mean.

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This function has two arguments.

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The first argument should describe what the test is performing.

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Jasmine and Karma will generate a test report.

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The value of this argument will appear in the report.

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The identifier should be short and concise.

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Let's type the following should pass sanity test.

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As I mentioned earlier, tests should be descriptive.

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Typically, testing libraries will name their functions.

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To help you describe the purpose of a test.

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For example, we can read this line of code like so it should pass sanity test.

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The second argument is a function that will run.

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When we test our application, we will pass in an arrow function.

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We're going to create what's called an assertion.

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In the software development world, an assertion is an expression that evaluates to either true or false.

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It's as simple as that.

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If the assertion we create evaluates to false, the test fails.

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If the assertion evaluates to true.

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The test passes.

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We're going to create an assertion that checks if true is equal to true.

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We can use a comparison operator to create this expression, but Jasmine has an even better solution

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inside the function.

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Add the following.

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Expect true to be true.

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Thi.

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We're using another global function defined by Jasmine called expect.

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This function will return an object with functions that are called matters.

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In the resource section of this lecture, I provide a link to a list of functions.

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The expect function takes in a value.

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It can be any type of value.

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It will return an object with methods you can use to perform a test on the value you passed in.

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These functions are referred to as matters.

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The purpose of these functions is to perform.

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A test on the value passed in this page provides a comprehensive list of available matters.

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One of the measures we're using is called to be truth.

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The to be truth.

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You matcher can check a boolean value.

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The Boolean value must be true.

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Let's head back to our editors.

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The tests we've written will always pass.

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That's the goal of a sanity test.

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We're creating a test that will always pass to verify our tools are working as intended.

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If the test doesn't pass, we'll know that there's a problem with the tools and not our tests.

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Let's switch over to the browser.

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If the test does not show up, you may need to restart the command.

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Jasmine has generated a test report.

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It's a list of tests that have been executed.

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In this list, the sanity test has passed.

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This response indicates that the test passed.

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We can begin to write more tests in the next set of lectures.

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Let's try writing more practical tests.