import { sveltekit } from "@sveltejs/kit/vite";
import { defineConfig } from "vitest/config";
import basicSsl from "@vitejs/plugin-basic-ssl";

export default defineConfig({
  plugins: [sveltekit(), basicSsl()],
  test: {
    include: ["src/**/*.{test,spec}.{js,ts}"],
    environment: "jsdom",
  },
  resolve: process.env.VITEST
    ? {
        conditions: ["browser"],
      }
    : undefined,
});

// classWDerivedCombiArray.svelte.ts
export class ClassWDerivedCombiArray {
  // two simple arrays as $state
  private _stateArray1 = $state<number[]>([]);
  private _stateArray2 = $state<number[]>([]);

  // one array that combines the previous two with $derived
  private _derivedCombiArray = $derived([
    ...this._stateArray1,
    ...this._stateArray2,
  ]);

  // the $derived length of the combined array
  private _derivedCombiArrayLength = $derived(this._derivedCombiArray.length);

  public get derivedCombiArray() {
    return this._derivedCombiArray;
  }

  public get derivedCombiArrayLength() {
    return this._derivedCombiArrayLength;
  }

  public pushToStateArray1() {
    this._stateArray1.push(1);
  }

  public pushToStateArray2() {
    this._stateArray2.push(2);
  }
}

// classWDerivedCombiArray.test.ts
import { describe, it, expect } from "vitest";
import { ClassWDerivedCombiArray } from "./classWDerivedCombiArray.svelte";

describe("test class with derived state", () => {
  it("reactively updates its state", () => {
    const obj = new ClassWDerivedCombiArray();

    expect(obj.derivedCombiArray).toEqual([]);

    // expect(obj.derivedCombiArrayLength).toEqual(0); // <-- If this test is executed, the next test below fails.

    obj.pushToStateArray1();

    // if the length test above is executed, this test fails with vitest
    // seeing obj.derivedCombiArray as [] instead of [1]
    expect(obj.derivedCombiArray).toEqual([1]);

    // expect(obj.derivedCombiArrayLength).toEqual(1); // <-- If this test is executed, the next test below fails.

    obj.pushToStateArray2();

    // if the length test above is executed, this test fails with vitest
    // seeing obj.derivedCombiArray as [1] instead of [1, 2]
    expect(obj.derivedCombiArray).toEqual([1, 2]);

    // ...the pattern goes on with every other push to one of the state arrays
  });
});