provider.test.js

import { test } from 'zora';
import {
  createProvider,
  fromClass,
  provideSymbol,
  singleton,
} from './provider.js';

test('instantiates an injectable, calling the factory', ({ eq }) => {
  const provide = createProvider({
    injectables: {
      a: () => 'a',
    },
  });

  const services = provide();

  eq(services.a, 'a');
});

test('instantiates an injectable, when it is a value', ({ eq }) => {
  const provide = createProvider({
    injectables: {
      a: 'a',
    },
  });

  const services = provide();

  eq(services.a, 'a');
});

test('everytime the getter is called a new instance is created', ({
  eq,
  isNot,
}) => {
  const provide = createProvider({
    injectables: {
      a: () => ({ prop: 'a' }),
    },
  });

  const services = provide();

  const instance1 = services.a;
  const { a: instance2 } = services;
  eq(instance1, { prop: 'a' });
  eq(instance2, { prop: 'a' });
  isNot(instance2, instance1);
});

test('singleton decorator makes sure an injectable is only instantiated once', ({
  eq,
  is,
}) => {
  const provider = createProvider({
    injectables: {
      a: ({ b }) => b,
      b: singleton(({ c }) => ({ c })),
      c: 'c',
    },
  });

  const services = provider();
  const instance1 = services.a;
  const instance2 = services.a;
  eq(instance1, { c: 'c' });
  eq(instance2, { c: 'c' });
  is(instance1, instance2);
});

test('resolves dependency graph, instantiating the transitive dependencies ', ({
  eq,
}) => {
  const provide = createProvider({
    injectables: {
      a: ({ b, c }) => b + '+' + c,
      b: () => 'b',
      c: ({ d }) => d,
      d: 'd',
    },
  });

  const services = provide();
  eq(services.a, 'b+d');
});

test('injection tokens can be symbols', ({ eq }) => {
  const aSymbol = Symbol('a');
  const bSymbol = Symbol('b');
  const cSymbol = Symbol('c');
  const dSymbol = Symbol('d');

  const provide = createProvider({
    injectables: {
      [aSymbol]: ({ [bSymbol]: b, [cSymbol]: c }) => b + '+' + c,
      [bSymbol]: () => 'b',
      [cSymbol]: ({ [dSymbol]: d }) => d,
      [dSymbol]: 'd',
    },
  });

  const services = provide();
  eq(services[aSymbol], 'b+d');
});

test(`only instantiates an injectable when required`, ({ eq, notOk, ok }) => {
  let aInstantiated = false;
  let bInstantiated = false;
  let cInstantiated = false;

  const provide = createProvider({
    injectables: {
      a: ({ b }) => {
        aInstantiated = true;
        return b;
      },
      b: () => {
        bInstantiated = true;
        return 'b';
      },
      c: () => {
        cInstantiated = true;
        return 'c';
      },
    },
  });

  const services = provide();
  const { a } = services;

  eq(a, 'b');
  ok(aInstantiated);
  ok(bInstantiated);
  notOk(cInstantiated);

  const { c } = services;
  eq(c, 'c');
  ok(cInstantiated);
});

test('provide function allows late binding', ({ eq }) => {
  const provide = createProvider({
    injectables: {
      a: ({ b }) => b,
    },
  });

  const { a } = provide({ b: () => 'b' });

  eq(a, 'b');
});

test('provide function allows to overwrite defined injectable', ({ eq }) => {
  const provide = createProvider({
    injectables: {
      a: ({ b }) => b,
      b: 'b',
    },
  });

  const { a } = provide({ b: `b'` });

  eq(a, `b'`);
});

test('gives a friendly message when it can not resolve a dependency', ({
  eq,
  fail,
}) => {
  const provide = createProvider({
    injectables: {
      a: ({ b }) => b,
      b: ({ c }) => c,
    },
  });

  try {
    const { a } = provide();
    fail('should not reach that statement');
  } catch (err) {
    eq(err.message, 'could not resolve injectable with injection token "c"');
  }
});

test('injectable is explicitly "undefined" then it is an actual injectable value', ({
  eq,
}) => {
  const provide = createProvider({
    injectables: {
      a: ({ b }) => b,
      b: ({ c }) => c,
      c: undefined,
    },
  });

  const { a } = provide();
  eq(a, undefined);
  const { a: aBis } = provide({
    c: ({ d }) => d,
    d: undefined,
  });
  eq(aBis, undefined);
});

test('provide is itself injected', ({ eq }) => {
  const withSession = (factory) => {
    return ({ [provideSymbol]: provide }) => {
      return factory(
        provide({
          session: true,
        })
      );
    };
  };

  const provide = createProvider({
    injectables: {
      usecaseA: withSession(
        ({ repository, service }) => repository + '&' + service
      ),
      usecaseB: ({ repository, service }) => repository + '&' + service,
      repository: ({ session }) =>
        session ? 'repositoryWithSession' : 'repository',
      service: 'some_service',
      session: undefined,
    },
  });

  const { usecaseA, usecaseB } = provide();

  eq(usecaseA, 'repositoryWithSession&some_service');
  eq(usecaseB, 'repository&some_service');
});

test('provide is itself injected, so are late bindings', ({ eq }) => {
  const withSession = (factory) => {
    return ({ [provideSymbol]: provide }) => {
      return factory(
        provide({
          session: true,
        })
      );
    };
  };

  const provide = createProvider({
    injectables: {
      usecaseA: withSession(
        ({ repository, service }) => repository + '&' + service
      ),
      usecaseB: ({ repository, service }) => repository + '&' + service,
      repository: ({ session }) =>
        session ? 'repositoryWithSession' : 'repository',
      session: undefined,
      // service is missing and will be late bound
    },
  });

  const { usecaseA, usecaseB } = provide({ service: 'some_service' });

  eq(usecaseA, 'repositoryWithSession&some_service');
  eq(usecaseB, 'repository&some_service');
});

test(`"api" defines the public API`, ({ eq }) => {
  const provide = createProvider({
    injectables: {
      a: ({ b }) => b,
      b: 'b',
      c: ({ b, d }) => `${b}+${d}`,
      d: 'd',
    },
    api: ['a', 'c'],
  });

  const moduleAPI = {
    ...provide(),
  };

  eq(Object.keys(moduleAPI), ['a', 'c']);
});

test('"fromClass" wraps the class within a factory', ({ eq }) => {
  class A {
    constructor({ b }) {
      this.b = b;
    }

    test() {
      return this.b.value;
    }
  }

  class B {
    constructor({ c }) {
      this.value = c;
    }
  }

  const provide = createProvider({
    injectables: {
      a: fromClass(A),
      b: fromClass(B),
      c: 'test',
    },
  });

  const { a } = provide();

  eq(a.test(), 'test');
});