Merge mocha with Typescript, and include the watch feature

Question

Merge mocha with Typescript, and include the watch feature

For my project, I have set up mocha to test my Typescript code. The issue arises when running the command:

mocha ts/test --compilers ts:typescript-require

Every time I make a change, it fails with an error message like this:

error TS2307: Cannot find module 'mocha'.

Oddly enough, if I simply run tsc, everything works fine (I have all the necessary type definitions and a tsconfig.json file). I even installed typescript-require for mocha.

What's even more confusing is that after I run the command once, it starts working as expected. However, when I use the watch mode with mocha:

mocha -w ts/test --compilers ts:typescript-require

It initially works but then fails upon subsequent runs. It's frustrating! Does anyone have any tips on setting up a stable configuration for testing and watching Typescript code with mocha?

typescript mocha.js

Answer 1

Answer №1

After encountering a similar need, I created ts-node (https://github.com/TypeStrong/ts-node). My requirement was to execute tests using different test runners and compiling to a separate directory wasn't sufficient as I also prefer embedding the test fixtures. This has evolved into a fully-featured node runtime for TypeScript, complete with a CLI that includes a neat little .type command feature. A README example demonstrates its usage with Mocha.

Currently, it operates entirely in memory, but there are plans to enhance it with additional flags to optimize its suitability for production environments (such as minimal runtime overhead and quick compilation startup). Share your experience using it!

Answer 2

After encountering a similar need, I created ts-node (https://github.com/TypeStrong/ts-node). My requirement was to execute tests using different test runners and compiling to a separate directory wasn't sufficient as I also prefer embedding the test fixtures. This has evolved into a fully-featured node runtime for TypeScript, complete with a CLI that includes a neat little .type command feature. A README example demonstrates its usage with Mocha.

Currently, it operates entirely in memory, but there are plans to enhance it with additional flags to optimize its suitability for production environments (such as minimal runtime overhead and quick compilation startup). Share your experience using it!

Answer 3

Answer №2

This code snippet monitors changes in typescript test files and executes them using ts-node (ensure ts-node is installed):

"scripts": {
"watch": "mocha -r ts-node/register test/*Test.ts --watch --watch-extensions ts"
}

Answer 4

This code snippet monitors changes in typescript test files and executes them using ts-node (ensure ts-node is installed):

"scripts": {
"watch": "mocha -r ts-node/register test/*Test.ts --watch --watch-extensions ts"
}

Answer 5

Answer №3

Personally, I found that including a prefix such as **/

mocha -r ts-node/register "test/**/*.ts" --watch --watch-files **/*

Additionally, if you need to include multiple specific folders or files:

mocha -r ts-node/register "test/**/*.ts" --watch --watch-files src/**/*,test/**/*

Answer 6

Personally, I found that including a prefix such as **/

mocha -r ts-node/register "test/**/*.ts" --watch --watch-files **/*

Additionally, if you need to include multiple specific folders or files:

mocha -r ts-node/register "test/**/*.ts" --watch --watch-files src/**/*,test/**/*

Answer 7

Answer №4

--extensions option has been deprecated in the latest version of Mocha 8.

Instead, you should use the --watch-files flag.

"scripts": {
    "watch": "mocha -r ts-node/register test/*Test.ts --watch --watch-files *.ts"
}

Answer 8

--extensions option has been deprecated in the latest version of Mocha 8.

Instead, you should use the --watch-files flag.

"scripts": {
    "watch": "mocha -r ts-node/register test/*Test.ts --watch --watch-files *.ts"
}

Answer 9

Answer №5

In Mocha 7, if you want to use the --watch flag, you need to define either --watch-files or --extension. You can choose one of the following configurations:

"scripts": {
    "watch": "mocha -r ts-node/register test/*Test.ts  --watch --extensions ts"
}

or

"scripts": {
    "watch": "mocha -r ts-node/register test/*Test.ts  --watch --watch-files test"
}

According to the Mocha official documentation :

--watch, -w Rerun tests on file changes.

The --watch-files and --watch-ignore options can be used to control which files are watched for changes.

Tests may be rerun manually by typing ⓡ ⓢ ⏎ (same shortcut as nodemon).

--watch-files New in v7.0.0

List of paths or globs to watch when --watch is set. If a file matching the given glob changes or is added or removed mocha will rerun all tests.

If the path is a directory all files and subdirectories will be watched.

By default all files in the current directory having one of the extensions provided by --extension and not contained in the node_modules or .git folders are watched.

The option can be given multiple times. The option accepts a comma-delimited list: --watch-files a,b is equivalent to --watch-files a --watch-files b

Answer 10

In Mocha 7, if you want to use the --watch flag, you need to define either --watch-files or --extension. You can choose one of the following configurations:

"scripts": {
    "watch": "mocha -r ts-node/register test/*Test.ts  --watch --extensions ts"
}

or

"scripts": {
    "watch": "mocha -r ts-node/register test/*Test.ts  --watch --watch-files test"
}

According to the Mocha official documentation :

--watch, -w Rerun tests on file changes.

The --watch-files and --watch-ignore options can be used to control which files are watched for changes.

Tests may be rerun manually by typing ⓡ ⓢ ⏎ (same shortcut as nodemon).

--watch-files New in v7.0.0

List of paths or globs to watch when --watch is set. If a file matching the given glob changes or is added or removed mocha will rerun all tests.

If the path is a directory all files and subdirectories will be watched.

By default all files in the current directory having one of the extensions provided by --extension and not contained in the node_modules or .git folders are watched.

The option can be given multiple times. The option accepts a comma-delimited list: --watch-files a,b is equivalent to --watch-files a --watch-files b

Answer 11

Answer №6

I have recently created a .mocharc.json file with the following contents:

{
  "extension": ["ts"],
  "spec": "test/**/*.ts",
  "require": "ts-node/register"
}

With this setup, I am now able to execute Mocha either for a single run or in watch mode:

$ npx mocha
or
$ npx mocha --watch

Of course, I can also include this configuration in my package.json file as a script.

Answer 12

I have recently created a .mocharc.json file with the following contents:

{
  "extension": ["ts"],
  "spec": "test/**/*.ts",
  "require": "ts-node/register"
}

With this setup, I am now able to execute Mocha either for a single run or in watch mode:

$ npx mocha
or
$ npx mocha --watch

Of course, I can also include this configuration in my package.json file as a script.

Merge mocha with Typescript, and include the watch feature

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

--watch-files New in v7.0.0

Answer №6

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