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105 lines
2.6 KiB
Markdown
105 lines
2.6 KiB
Markdown
# Testing
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Deno has a built-in test runner that you can use for testing JavaScript or
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TypeScript code.
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## Writing tests
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To define a test you need to call `Deno.test` with a name and function to be
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tested:
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```ts
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Deno.test("hello world", () => {
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const x = 1 + 2;
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if (x !== 3) {
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throw Error("x should be equal to 3");
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}
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});
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```
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There are some useful assertion utilities at https://deno.land/std/testing to
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make testing easier:
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```ts
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import { assertEquals } from "https://deno.land/std/testing/asserts.ts";
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Deno.test("hello world", () => {
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const x = 1 + 2;
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assertEquals(x, 3);
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});
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```
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### Async functions
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You can also test asynchronous code by passing a test function that returns a
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promise. For this you can use the `async` keyword when defining a function:
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```ts
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Deno.test("async hello world", async () => {
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const x = 1 + 2;
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// await some async task
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await delay(100);
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if (x !== 3) {
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throw Error("x should be equal to 3");
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}
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});
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```
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### Resource and async op sanitizers
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Certain actions in Deno create resources in the resource table
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([learn more here](./contributing/architecture.md)). These resources should be
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closed after you are done using them.
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For each test definition the test runner checks that all resources created in
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this test have been closed. This is to prevent resource 'leaks'. This is enabled
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by default for all tests, but can be disabled by setting the `sanitizeResources`
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boolean to false in the test definition.
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The same is true for async operation like interacting with the filesystem. The
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test runner checks that each operation you start in the test is completed before
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the end of the test. This is enabled by default for all tests, but can be
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disabled by setting the `sanitizeOps` boolean to false in the test definition.
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```ts
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Deno.test({
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name: "leaky test",
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fn() {
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Deno.open("hello.txt");
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},
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sanitizeResources: false,
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sanitizeOps: false,
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});
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```
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### Ignoring tests
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Sometimes you want to ignore tests based on some sort of condition (for example
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you only want a test to run on Windows). For this you can use the `ignore`
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boolean in the test definition. If it is set to true the test will be skipped.
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```ts
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Deno.test({
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name: "do macOS feature",
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ignore: Deno.build.os !== "darwin",
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fn() {
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doMacOSFeature();
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},
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});
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```
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## Running tests
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To run the test, call `deno test` with the file that contains your test
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function:
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```shell
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deno test my_test.ts
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```
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You can also omit the file name, in which case all tests in the current
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directory (recursively) that match the glob `{*_,}test.{js,ts,jsx,tsx}` will be
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run. If you pass a directory, all files in the directory that match this glob
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will be run.
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