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");
  }) 
})

@taras thanks! Updated.