noCatchErrorInEffectChainRule.ts

// Dependencies:
import { tsquery } from '@phenomnomnominal/tsquery';
import { RuleFailure, Rules } from 'tslint';
import { SourceFile } from 'typescript';

// Constants:
const CATCH_ERROR_QUERY = 'ClassDeclaration > PropertyDeclaration:has(Decorator Identifier[name="Effect"]) > CallExpression > CallExpression > Identifier[name="catchError"]';

const FAILURE_MESSAGE = `

    Using "catchError" on the outermost Observable chain of an effect can 
    cause the entire stream of actions to break.
    
    See https://medium.com/city-pantry/handling-errors-in-ngrx-effects-a95d918490d9 for more details.

`;

export class Rule extends Rules.AbstractRule {
    public apply(sourceFile: SourceFile): Array<RuleFailure> {
        return tsquery(sourceFile, CATCH_ERROR_QUERY).map(result => {
            return new RuleFailure(result.getSourceFile(), result.getStart(), result.getEnd(), FAILURE_MESSAGE, this.ruleName);
        });
    }
}