1 files changed, 98 insertions, 0 deletions
diff --git a/src/adapters/history/index.test.ts b/src/adapters/history/index.test.ts
new file mode 100644
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+++ b/src/adapters/history/index.test.ts
@@ -0,0 +1,98 @@
+import { describe, expect, it } from "vitest";
+import { createHistoryAdapter, type HistoryWindow } from "./index";
+
+/**
+ * A minimal in-memory `HistoryWindow` fake for deterministic tests. `pathname`
+ * is a closure variable reflected through the `location` getter; `back(url)`
+ * simulates an external navigation (back/forward): it sets the path + fires the
+ * popstate listeners.
+ */
+function fakeWindow(initial = "/"): HistoryWindow & { back(url: string): void } {
+  let pathname = initial;
+  const popstateListeners = new Set<() => void>();
+  return {
+    get location() {
+      return {
+        get pathname() {
+          return pathname;
+        },
+      };
+    },
+    history: {
+      pushState(_data, _unused, url) {
+        if (typeof url === "string") pathname = url;
+      },
+      replaceState(_data, _unused, url) {
+        if (typeof url === "string") pathname = url;
+      },
+    },
+    addEventListener(type, listener) {
+      if (type === "popstate") popstateListeners.add(listener);
+    },
+    removeEventListener(type, listener) {
+      if (type === "popstate") popstateListeners.delete(listener);
+    },
+    back(url: string) {
+      pathname = url;
+      for (const l of popstateListeners) l();
+    },
+  };
+}
+
+describe("createHistoryAdapter", () => {
+  it("reads the current path", () => {
+    const w = fakeWindow("/my-ws");
+    const h = createHistoryAdapter({ window: w });
+    expect(h.path).toBe("/my-ws");
+  });
+
+  it("navigate updates the path + notifies subscribers", () => {
+    const w = fakeWindow("/");
+    const h = createHistoryAdapter({ window: w });
+    const seen: string[] = [];
+    h.subscribe((p) => seen.push(p));
+    h.navigate("/default");
+    expect(h.path).toBe("/default");
+    expect(seen).toEqual(["/default"]);
+  });
+
+  it("replace updates the path WITHOUT notifying", () => {
+    const w = fakeWindow("/");
+    const h = createHistoryAdapter({ window: w });
+    const seen: string[] = [];
+    h.subscribe((p) => seen.push(p));
+    h.replace("/default");
+    expect(h.path).toBe("/default");
+    expect(seen).toEqual([]);
+  });
+
+  it("fires subscribers on popstate (back/forward)", () => {
+    const w = fakeWindow("/");
+    const h = createHistoryAdapter({ window: w });
+    const seen: string[] = [];
+    h.subscribe((p) => seen.push(p));
+    w.back("/my-ws");
+    expect(seen).toEqual(["/my-ws"]);
+  });
+
+  it("unsubscribe stops notifications (navigate + popstate)", () => {
+    const w = fakeWindow("/");
+    const h = createHistoryAdapter({ window: w });
+    const seen: string[] = [];
+    const unsub = h.subscribe((p) => seen.push(p));
+    unsub();
+    h.navigate("/default");
+    w.back("/other");
+    expect(seen).toEqual([]);
+  });
+
+  it("degrades to a no-op adapter when there is no location (SSR)", () => {
+    const w = { location: undefined } as unknown as HistoryWindow;
+    const h = createHistoryAdapter({ window: w });
+    expect(h.path).toBe("/");
+    const seen: string[] = [];
+    h.subscribe((p) => seen.push(p));
+    h.navigate("/default");
+    expect(seen).toEqual([]);
+  });
+});