external-exceptions-handler.spec.ts

import { expect } from 'chai';
import { of } from 'rxjs';
import * as sinon from 'sinon';
import { ExternalExceptionsHandler } from '../../exceptions/external-exceptions-handler';
import { ExternalExceptionFilter } from '../../exceptions/external-exception-filter';

describe('ExternalExceptionsHandler', () => {
  let handler: ExternalExceptionsHandler;

  beforeEach(() => {
    handler = new ExternalExceptionsHandler();

    // eslint-disable-next-line @typescript-eslint/ban-ts-comment
    // @ts-ignore The 'logger' property is private but we want to avoid showing useless error logs
    ExternalExceptionFilter.logger.error = () => {};
  });

  describe('next', () => {
    it('should method returns expected stream with message when exception is unknown', () => {
      const error = new Error();
      expect(() => handler.next(error, null)).to.throw(error);
    });
    describe('when "invokeCustomFilters" returns value', () => {
      const observable$ = of(true);
      beforeEach(() => {
        sinon.stub(handler, 'invokeCustomFilters').returns(observable$ as any);
      });
      it('should return observable', () => {
        const result = handler.next(new Error(), null);
        expect(result).to.be.eql(observable$);
      });
    });
  });
  describe('setCustomFilters', () => {
    const filters = ['test', 'test2'];
    it('should set custom filters', () => {
      handler.setCustomFilters(filters as any);
      expect((handler as any).filters).to.be.eql(filters);
    });
    it('should throws exception when passed argument is not an array', () => {
      expect(() => handler.setCustomFilters(null)).to.throw();
    });
  });
  describe('invokeCustomFilters', () => {
    describe('when filters array is empty', () => {
      it('should return identity', () => {
        expect(handler.invokeCustomFilters(null, null)).to.be.null;
      });
    });
    describe('when filters array is not empty', () => {
      let filters, funcSpy;
      class TestException {}
      class AnotherTestException {}

      beforeEach(() => {
        funcSpy = sinon.spy();
      });
      describe('when filter exists in filters array', () => {
        beforeEach(() => {
          filters = [{ exceptionMetatypes: [TestException], func: funcSpy }];
          (handler as any).filters = filters;
        });
        it('should call funcSpy', () => {
          handler.invokeCustomFilters(new TestException(), null);
          expect(funcSpy.notCalled).to.be.false;
        });
        it('should call funcSpy with exception and response passed as an arguments', () => {
          const exception = new TestException();
          handler.invokeCustomFilters(exception, null);
          expect(funcSpy.calledWith(exception)).to.be.true;
        });
        it('should return stream', () => {
          expect(handler.invokeCustomFilters(new TestException(), null)).to.be
            .not.null;
        });
      });
      describe('when filter does not exists in filters array', () => {
        beforeEach(() => {
          filters = [
            { exceptionMetatypes: [AnotherTestException], func: funcSpy },
          ];
          (handler as any).filters = filters;
        });
        it('should not call funcSpy', () => {
          handler.invokeCustomFilters(new TestException(), null);
          expect(funcSpy.notCalled).to.be.true;
        });
        it('should return null', () => {
          expect(handler.invokeCustomFilters(new TestException(), null)).to.be
            .null;
        });
      });
    });
  });
});