include ../../../../_includes/_util-fns

:markdown
  We’ll write our tests with the [Jasmine test framework](http://jasmine.github.io/2.3/introduction.html).
  We’ll start by getting *some* tests to work - *any* tests at all.

  We will learn
    - basic Jasmine testing skills
    - to run our tests in the browser
    - to write simple Jasmine tests in TypeScript
    - to debug a test in the browser

  **Create a new project folder** perhaps called `angular2-unit-testing`.
.l-main-section
:markdown
  ## Install npm packages locally

  Next follow all of  the steps prescribed in  “Install npm packages locally” of the
  [QuickStart](../quickstart.html).

  We’ll also add the Jasmine package via `npm`:

pre.prettyprint.lang-bash
   code npm install jasmine-core --save-dev --save-exact

.alert.is-important
  :markdown
    Be sure to install `jasmine-core` , not `jasmine`!

:markdown
  **Create a sub-folder `src` ** for our tests and then **cd into it**.

  We are going to **display and control our tests in the browser**.

.l-sub-section
  :markdown
    The browser is nice during development of a few tests. It’s not the best venue for working with a lot of tests and it won’t do at all for build automation. We’ll switch to the karma test-runner when the time comes. But the browser will do for now.

.l-main-section
:markdown
  Create a new file called`unit-tests.html` and enter the following:
  ```
  <html>
  <head>
    <title>1st Jasmine Tests</title>
    <link rel="stylesheet" href="../node_modules/jasmine/lib/jasmine.css">

    <script src="../node_modules/jasmine/lib/jasmine.js"></script>
    <script src="../node_modules/jasmine/lib/jasmine-html.js"></script>
    <script src="../node_modules/jasmine/lib/boot.js"></script>
  </head>

  <body>
  </body>

  </html>
  ```

  In the head we have three Jasmine scripts and one Jasmine css file. That’s the foundation for running any tests.

  We’ll write our first test with inline JavaScript inside the body tag:

  ```
  <script>
    it('true is true', function(){ expect(true).toEqual(true); });
  </script>
  ```

  Now open `unit-tests.html` in a browser and see the Jasmine HTML test output:

figure.image-display
    img(src='/resources/images/devguide/jasmine-testing-101/jasmine-1-spec-0-failures.png' style="height:170px;" alt="Jasmine HTML test output")

:markdown
  It doesn’t get much simpler than that!

  ## First TypeScript Test
  Perhaps too simple. We won’t write our entire test suite inside one HTML file.
  Let’s **extract** that line of test code to a **new file in `src` called `1st.spec.ts` ** .

.l-sub-section
  :markdown
    Among Jasmine developers, a test is known as a “spec” and test filenames include the word “spec”.  We’ll stick with that convention.

.l-main-section
:markdown
  The test we wrote is valid TypeScript because any JavaScript is valid TypeScript. But let’s make it more modern with an arrow function:
  ```
  it('true is true', () => expect(true).toEqual(true));
  ```
  Now modify `unit-tests.html` to load the script:
  ```
  <script src="1st.spec.js"></script>
  ```
  Hold on!   We wrote a TypeScript file but we’re loading a JavaScript file?

  That’s a reminder that we need to compile our TypeScript test files as we do our TypeScript application files.  Do that next.

  ## Prepare for TypeScript

  As we’ve seen before, we first have to tell the compiler how to compile our TypeScript files with
  a ** `tsconfig.json` **.

  We can copy one from an application we wrote previously and paste it into our src sub-folder.
  It should look something like this:

  ```
  {
    "compilerOptions": {
      "target": "ES5",
      "module": "commonjs",
      "sourceMap": true,
      "emitDecoratorMetadata": true,
      "experimentalDecorators": true
    }
  }
  ```
  ## Compile and Run

  Compile in the terminal window using the npm script command

pre.prettyprint.lang-bash
  code npm run tsc

.alert.is-helpful
  :markdown
    Our editor and the compiler may complain that they don’t know
    what `it` and `expect` are because they lack the typing files that describe Jasmine.
    We can ignore those annoying complaints for now as they are harmless.

:markdown
  If we reload the browser, we should see the same Jasmine test-runner output as before.

  We’ll be evolving these tests rapidly and it would be nice to have the browser refresh automatically as we make changes and recompile.

  Let’s launch with **live-server** in a second terminal window:

pre.prettyprint.lang-bash
  code npm start

:markdown
  Now navigate to `1st-tests.html`

  We should get the same Jasmine test-runner output as before.

  ## Add a describe and another test

  We can’t tell what file produced these test results. We only have one file at the moment but soon we’ll write more.

  We should wrap this test something that identifies the file. In Jasmine that “something” is a `describe` function.  Every test file should have at least one `describe` that identifies the file holding the test(s).

  Here’s what our revised `1st.spec.ts` looks like when wrapped in a `describe`:
  ```
  describe('1st tests', () => {

    it('true is true', () => expect(true).toEqual(true));

  });
  ```
  And here’s how the test report displays it.

figure.image-display
    img(src='/resources/images/devguide/jasmine-testing-101/test-report-1-spec-0-failures.png' style="height:100px;" alt="1 spec, 0 failures")

:markdown
  Let’s add another Jasmine test to `1st.spec.ts`
  ```
  it('null is not the same thing as undefined',
    () => expect(null).not.toEqual(undefined)
  );
  ```
  You knew that right?  Let’s prove it with this test. The browser should refresh after you paste that test, and show:

figure.image-display
    img(src='/resources/images/devguide/jasmine-testing-101/test-report-2-specs-0-failures.png' style="height:100px;" alt="refreshed 2 specs, 0 failures")

:markdown
  What does a failing test look like? Remove the `.not`. The browser refreshes and shows:

figure.image-display
    img(src='/resources/images/devguide/jasmine-testing-101/test-report-2-specs-1-failure.png' style="height:190px;" alt="failing test 2 specs, 1 failure")

:markdown
  Click the `Spec List` link just below “2 specs, 1 failure” to see the summary again:

figure.image-display
    img(src='/resources/images/devguide/jasmine-testing-101/spec-list-2-specs-1-failure.png' style="height:140px;" alt="2 specs, 1 failure")

:markdown
  We can re-run just the failing test by double-clicking it.  Try it!

  ## Debug the test
  Suppose we didn’t know what was going on.  We can debug it in the browser.

    - Open the browser’s “Developer Tools” (F12 or Ctrl-Shift-I).
    - Pick the “sources” section
    - Open the `1st.spec.ts` test file (Ctrl-P, then start typing the name of the file).
    - Set a breakpoint on the second line of the failing test
    - Refresh the browser … and it stops at our breakpoint.
    - Open the console window at the bottom  (press Esc)
    - Type `null === undefined` … … and we should see this:

figure.image-display
    img(src='/resources/images/devguide/jasmine-testing-101/null-to-equal-undefined.png' style="height:500px;" alt="null === undefined")

:markdown
  How about that!  They really aren’t equal.
    - remove the breakpoint (right-click in the “Breakpoints” section and chose “Remove breakpoint”)
    - Click the “play” icon to resume the test  (or F8)

  And the test finishes.  Close the browser tools (click the close box or press F12 or Ctrl-Shift-I)

  Fix the test (restore the `.not`);  the browser should refresh automatically and all tests pass.

  Congratulations … you’ve completed Jasmine testing 101.

  ## Learn more
  Learn more about basic Jasmine testing here
  [Resources TBD](./#)

  ## What’s Next?
  Now that we’re familiar with Jasmine on its own, we’re ready to test an application.

  What application? We introduce you to that app in the next chapter.