feat: pybot 新增 @Camera 摄像头块——picamera2 惰性导入，后台守护线程维护有界帧队列（满丢最旧）

pybot/tests/test_camera.py

@@ -0,0 +1,100 @@
+"""Camera 测试：有界帧队列（满丢最旧）、守护线程生命周期、dry_run、.mt 接入
+
+全部经注入 grabber 运行，不碰 picamera2 / 真实摄像头。
+"""
+
+import time
+
+from pybot.hd.camera import Camera
+from pybot.robot import RobotStruct
+
+
+class FakeGrabber:
+    """假帧源：产出递增序号帧"""
+
+    def __init__(self):
+        self.count = 0
+
+    def __call__(self):
+        self.count += 1
+        return self.count
+
+
+CAMERA_MT = """
+@Camera
+ name  width  height  framerate  capacity;
+ cam0    320      240        15         2;
+@
+
+@Action
+cam0.frame;
+0;
+@
+"""
+
+
+def test_queue_capacity_drops_oldest():
+    cam = Camera(capacity=3, grabber=FakeGrabber())
+    for _ in range(5):
+        cam._grab_once()
+    assert [f for _, f in cam.snapshot()] == [3, 4, 5]  # 容量 3，丢最旧
+    assert cam.latest()[1] == 5
+    assert cam.size == 3
+
+
+def test_latest_empty():
+    assert Camera(grabber=FakeGrabber()).latest() is None
+    assert Camera(grabber=FakeGrabber()).snapshot() == []
+
+
+def test_daemon_lifecycle():
+    cam = Camera(framerate=200.0, capacity=10, grabber=FakeGrabber())
+    cam.setup()                     # 注入 grabber 时不碰硬件
+    cam.start_daemon()
+    time.sleep(0.1)
+    cam.stop_daemon()
+    cam.wait_daemon()
+    assert cam.size > 0
+    n = cam.size
+    time.sleep(0.05)
+    assert cam.size == n            # 停止后队列不再增长
+
+
+def test_grab_failure_keeps_daemon_alive(caplog):
+    def bad_grabber():
+        raise RuntimeError("boom")
+    cam = Camera(framerate=200.0, capacity=2, grabber=bad_grabber)
+    cam.start_daemon()
+    time.sleep(0.05)
+    cam.stop_daemon()
+    cam.wait_daemon()
+    assert cam.size == 0
+    assert any("grab failed" in r.message for r in caplog.records)
+
+
+def test_dry_run_no_hardware():
+    cam = Camera(dry_run=True)
+    cam.setup()
+    cam.start_daemon()              # 空操作
+    cam.stop_daemon()
+    cam.wait_daemon()
+    cam.close()
+    assert cam.latest() is None
+
+
+def test_camera_var_from_matrix():
+    robot = RobotStruct(CAMERA_MT, dry_run=True)
+    cam = robot.M["cam0"].camera
+    assert (cam.width, cam.height) == (320, 240)
+    assert cam.framerate == 15.0
+    assert cam.capacity == 2
+    robot.deactive()
+
+
+def test_camera_full_lifecycle_in_robot():
+    """dry_run 下 build/run/destroy 全流程不碰硬件"""
+    robot = RobotStruct(CAMERA_MT, dry_run=True)
+    robot.active()                  # build：dry_run 空操作
+    assert robot.M["cam0"].play({}) is None
+    robot.run()                     # @Action 引用 cam0.frame 不报错
+    robot.deactive()