A testing scope for Effection to help writing tests

01-test-scope.ts

import { run, type Operation } from "effection";

export interface TestScope {
  /**
   * Call from your runner's "beforeEach" or equivalent 
   */
  addSetup(op: () => Operation<void>): void;
  
  /**
   * Call from runner's `it()` or equivalent;
   */
  runTest(op: () => Operation<void>): Promise<void>;
}

export function createTestScope(): TestScope {
  let setup = [] as Array<() => Operation<void>>;

  return {
    addSetup(op) {
      setup.push(op);
    },

    runTest(op) {
      return run(function*() {
	for (let step of setup) {
	  yield* step();
	}
	yield* op();
      })
    },
  };
}

02-deno-bdd.ts

import * as bdd from "https://deno.land/[email protected]/testing/bdd.ts";
import { TestScope, createTestScope } from "./test-scope.ts";
import type { Operation } from "effection";

let scope: TestScope | void = void(0);

// Integrate test scope with the Deno test runner by wrapping the `describe()`, `it()` and `beforeEach()` methods.
function describeWithScope<T>(...args: bdd.DescribeArgs<T>): bdd.TestSuite<T> {

  let [name, def] = args;
  return bdd.describe(name as string, () => {
    bdd.beforeEach(() => {
      if (!scope) {
	scope = createTestScope();
      }
    });

    if (def && typeof def === "function") {
      def();
    }
  });
}

describeWithScope.only = bdd.describe.only;
describeWithScope.ignore = bdd.describe.ignore;

export const describe: typeof bdd.describe = describeWithScope;

export function beforeEach(op: () => Operation<void>): void { 
  bdd.beforeEach(() => scope!.addSetup(op));
}

export function it(desc: string, op?: () => Operation<void>): void {
  if (op) {
    return bdd.it(desc, () => scope!.runTest(op));
  } else {
    return bdd.it.ignore(desc, () => {});
  }
}

it.only = function only(desc: string, op?: () => Operation<void>): void {
  if (op) {
    return bdd.it.only(desc, () => scope!.runTest(op));
  } else {
    return bdd.it.ignore(desc, () => {});
  }
};

03-unit.test.ts

import { createContext } from "effection";
import { describe, it, beforeEach } from "./02-deno.bdd.ts";

const context = createContext<string>("some-string");

describe("scenario", () => {
  beforeEach(function*() {
    yield* context.set("Hello World");
  });
  
  it("does something with context", function*() {
    expect(yield* context).toEqual("Hello World");
  }) 
})

In effection 3 the beforeEach function should be:

beforeEach(function*(scope: Scope) {
  yield* scope.set(context, 'Hello World');
});

Thanks @floratmin! I've updated the gist.

@floratmin This got me to thinking: why not just run the beforeEach() inside the same scope as the test itself is running? This grossly simplifies things by just storing all the setup steps and running them right before the body of the test itself.

Among other things, there is no need to even have a destroy() at all because only ever one task is being executed, the actual test itself.

the only time that I could see keeping a scope around would be if you wanted to have a beforeAll() hook which this mechanism does not currently support.

@cowboyd 02-deno-bdd.ts file is missing imports

-import { TestScope } from "./test-scope.ts";
+import { TestScope, createTestScope } from "./test-scope.ts";
+import type { Operation } from "effection";

@taras thanks! Updated.