test(commands): cover viewport command flow

commands/viewport.test.ts

@@ -0,0 +1,44 @@
+import { describe, expect, test } from "bun:test";
+import { createInitialAppState } from "@editor/initial-state";
+import {
+  viewportPanCommand,
+  viewportResetCommand,
+  viewportSetSizeCommand,
+  viewportSetZoomCommand,
+  viewportZoomAroundPointCommand,
+} from "./viewport";
+
+const context = () => ({ state: createInitialAppState("Test") });
+
+describe("viewport commands", () => {
+  test("pans viewport center", () => {
+    const next = viewportPanCommand.execute(context(), { delta: { x: 10, y: -5 } });
+    expect(next.editor.viewport.center).toEqual({ x: 10, y: -5 });
+  });
+
+  test("sets zoom with minimum clamp", () => {
+    const next = viewportSetZoomCommand.execute(context(), { zoom: -1 });
+    expect(next.editor.viewport.zoom).toBe(0.01);
+  });
+
+  test("sets non-negative viewport size", () => {
+    const next = viewportSetSizeCommand.execute(context(), { w: 800, h: -1 });
+    expect(next.editor.viewport.size).toEqual({ w: 800, h: 0 });
+  });
+
+  test("zooms around a viewport point", () => {
+    const state = viewportSetSizeCommand.execute(context(), { w: 100, h: 100 });
+    const next = viewportZoomAroundPointCommand.execute({ state }, { zoom: 2, point: { x: 100, y: 50 } });
+
+    expect(next.editor.viewport.zoom).toBe(2);
+    expect(next.editor.viewport.center).toEqual({ x: 25, y: 0 });
+  });
+
+  test("resets viewport but preserves size", () => {
+    const sized = viewportSetSizeCommand.execute(context(), { w: 640, h: 480 });
+    const panned = viewportPanCommand.execute({ state: sized }, { delta: { x: 4, y: 8 } });
+    const next = viewportResetCommand.execute({ state: panned }, undefined);
+
+    expect(next.editor.viewport).toEqual({ center: { x: 0, y: 0 }, zoom: 1, rotation: 0, size: { w: 640, h: 480 } });
+  });
+});