add some tests to store class

tests/store.test.ts

@@ -0,0 +1,56 @@
+import { Store } from "../src/store";
+import { nextMicroTick } from "./helpers";
+
+describe("basic use", () => {
+  test("commit a mutation", () => {
+    const state = { n: 1 };
+    const mutations = {
+      inc(state, delta) {
+        state.n += delta;
+      }
+    };
+    const store = new Store({ state, mutations });
+
+    expect(store.state.n).toBe(1);
+    store.commit("inc", 14);
+    expect(store.state.n).toBe(15);
+  });
+
+  test("dispatch an action", () => {
+    const state = { n: 1 };
+    const mutations = {
+      inc(state, delta) {
+        state.n += delta;
+      }
+    };
+    const actions = {
+      inc({ commit }, delta) {
+        commit("inc", delta);
+      }
+    };
+    const store = new Store({ state, mutations, actions });
+
+    expect(store.state.n).toBe(1);
+    store.dispatch("inc", 14);
+    expect(store.state.n).toBe(15);
+  });
+
+  test("multiple commits trigger one update", async () => {
+    let updateCounter = 0;
+    const state = { n: 1 };
+    const mutations = {
+      inc(state, delta) {
+        state.n += delta;
+      }
+    };
+    const store = new Store({ state, mutations });
+    store.on("update", null, () => updateCounter++);
+
+    store.commit("inc", 14);
+    expect(updateCounter).toBe(0);
+    store.commit("inc", 50);
+    expect(updateCounter).toBe(0);
+    await nextMicroTick();
+    expect(updateCounter).toBe(1);
+  });
+});