Some eslint rules for working with NestJs projects

To install

npm install --save-dev @darraghor/eslint-plugin-nestjs-typed

Then update your eslint with the plugin import and add the recommended rule set

module.exports = {
    env: {
        es6: true,
    },
    extends: ["plugin:@darraghor/nestjs-typed/recommended"],
    parser: "@typescript-eslint/parser",
    parserOptions: {
        project: ["./tsconfig.json"],
        sourceType: "module",
        ecmaVersion: "es2019",
    },
    plugins: ["@darraghor/nestjs-typed"],
};

Note: the injectables test scans your whole project. It's best to filter out ts things that don't matter - use filterFromPaths configuration setting for this. There are some defaults already applied. See details below.

Note: You can easily turn off all the swagger rules if you don't use swagger by adding the no-swagger rule set AFTER the recommended rule set.

// all the other config
    extends: ["plugin:@darraghor/nestjs-typed/recommended",
    "plugin:@darraghor/nestjs-typed/no-swagger"
    ],
    // more config

Rules

Rule: provided-injected-should-match-factory-parameters

Checks that there are the same number of injected items in a Provider that are passed to the factory method

Passes (Myservide injected and myservice used in factory params)

export const MyOtherInjectableProvider: NotAProvider = {
    provide: MyOtherInjectable,
    useFactory: async (config: MyService): Promise<MyOtherInjectable> => {
        return new MyOtherInjectable();
    },
    inject: [MyService],
};

Fails (SecondService is not used in the factory)

export const MyOtherInjectableProvider: Provider = {
    provide: MyOtherInjectable,
    useFactory: async (config: MyService): Promise<MyOtherInjectable> => {
        return new MyOtherInjectable();
    },
    inject: [MyService, SecondService],
};

Rule: injectable-should-be-provided

Checks that a class marked with @Injectable is injected somewhere or used in a provider.

Fails if a thing marked as @Injectable is not in the providers of a module or provides in a provider.

There is some additional configuration you can provide for this rule. This is the default setting. You should overrride this with your src directory and any strings to filter out from paths (note that the filterFromPaths are NOT globs - just matched strings).

    "@darraghor/nestjs-typed/injectable-should-be-provided": [
            "error",
            {
                src: ["src/**/*.ts"],
                filterFromPaths: ["node_modules", ".test.", ".spec."],
            },
        ],

Rule: api-property-matches-property-optionality

This checks that you have added the correct api property decorator for your swagger documents. There are specific decorators for optional properties

The following FAILS because this is an optional property and should have @ApiPropertyOptional

class TestClass {
    @Expose()
    @ApiProperty()
    thisIsAStringProp?: string;
}

The following FAILS because this is a required property and should have @ApiProperty

class TestClass {
    @Expose()
    @ApiPropertyOptional()
    thisIsAStringProp!: string;
}