eslint-plugin-cdk

Eslint plugin for the CDK repository. Contains rules that need to be applied specific to the CDK repository.

Rules

• invalid-cfn-imports: Ensures that imports of Cfn<Resource> L1 resources come from the stable aws-cdk-lib package and not the alpha packages. Rule only applies to alpha modules.

• no-core-construct: Forbid the use of Construct and IConstruct from the "@aws-cdk/core" module. Instead use Construct and IConstruct from the "constructs" module. Rule only applies to typescript files under the test/ folder.

• no-invalid-path: Checks paths specified using path.join() for validity, including not going backwards ('..') multiple times in the path and not going backwards beyond a package's package.json.

• no-literal-partition: Forbids the use of literal partitions (usually aws). Instead, use Aws.PARTITION to ensure that the code works for other partitions too.

• consider-promise-all: when using Promise.all(), attest that there is no unbounded parallelism.

• no-throw-default-error: Forbid throwing the default JavaScript error type. Instead a custom typed error should be thrown.

• no-this-in-static: Forbid the use of the keywords this and super in static methods.

How to use these rules

Import the plugin and declare rules with the @cdklabs prefix:

1module.exports = {
2  plugins: [
3    // ... other plugins
4    '@cdklabs',
5  ],
6  rules: {
7    '@cdklabs/no-throw-default-error': [ 'error' ],
8  }
9}

How to add new rules

• Make a new file in lib/rules. It should export one function called create. The create function should return a visitor object.
• Add the new file to lib/index.ts.
• Add a fixture directory under test/fixtures/<rule name>. Copy and adjust an eslintrc.js file from another test.
• Add a testing .ts file, and be sure to add either an expected.ts or an .error.txt variant as well!
• You can now run the test in debugging mode (make sure to have npx tsc -w running, then from a debugging terminal, npx jest --no-coverage -it 'your rule name'), set a breakpoint, and inspect the typeless objects.

Use https://ts-ast-viewer.com/ to get a feel for the AST you're trying to analyze. Note that eslint uses estree to model AST nodes (not the TypeScript AST nodes), but they are often comparable. Add type-testing TypeScript helpers to type-checkers.ts for typing assistance.

To activate it for real on the repo, also add it to cdk-build-tools/config/eslintrc.js.