State dependencies

packages/core/src/__tests__/new-gen/deps.test.ts

@@ -0,0 +1,42 @@
+import { createSource } from "../../AsyncState";
+import {expect} from "@jest/globals";
+
+describe("instance deps", () => {
+  // test to shape the API of dependencies and how it should work
+  // dependencies are state instances that we will replay when the state changes
+  // the API would to allow deps gathering from
+  // - source creation via createSource
+  // - subscriptions via useAsync and useData
+
+  // The challenges:
+  // - some deps may be present from source and hooks, we should run them once
+  // - some deps may not be present at the moment of declaration, until invocation
+
+  // Open questions:
+  // - should we replay only, or support run too run via args (types!!)
+  // - should we always run or only when there is an active subscription
+
+  // Needed features:
+  // - run or not based on state and status
+  // - integrate with all existing features seamlessly
+  // - declare deps by: key or source
+  // - provide array of deps
+  it.skip("should automatically replay when state changes", () => {
+    let main = createSource<number>("main-1", null);
+    let spy = jest.fn().mockImplementation(({args}) => args[0]);
+    let dep1 = createSource<number, [number]>("dep-1", spy);
+    dep1.run(15);
+
+    expect(dep1.getState().data).toBe(15);
+    expect(spy).toHaveBeenCalledTimes(1);
+    expect(spy.mock.calls[0][0].args).toEqual([15]);
+    spy.mockClear();
+
+    main.setData(1);
+    expect(spy).toHaveBeenCalledTimes(1);
+    expect(spy.mock.calls[0][0].args).toEqual([15]);
+  });
+  it.skip("not run when condition is falsy", () => {
+
+  });
+});