Various tests for reactivity (#1223)

Author: darrenburns

tests/test_reactive.py

@@ -1,26 +1,240 @@
+import asyncio
+
+import pytest
+
 from textual.app import App, ComposeResult
-from textual.reactive import reactive
+from textual.reactive import reactive, var
+from textual.widget import Widget
 
+OLD_VALUE = 5_000
+NEW_VALUE = 1_000_000
 
-class WatchApp(App):
 
-    count = reactive(0, init=False)
+async def test_watch():
+    """Test that changes to a watched reactive attribute happen immediately."""
 
-    test_count = 0
+    class WatchApp(App):
+        count = reactive(0, init=False)
 
-    def watch_count(self, value: int) -> None:
-        self.test_count = value
+        watcher_call_count = 0
 
+        def watch_count(self, value: int) -> None:
+            self.watcher_call_count = value
 
-async def test_watch():
-    """Test that changes to a watched reactive attribute happen immediately."""
     app = WatchApp()
     async with app.run_test():
         app.count += 1
-        assert app.test_count == 1
+        assert app.watcher_call_count == 1
         app.count += 1
-        assert app.test_count == 2
+        assert app.watcher_call_count == 2
         app.count -= 1
-        assert app.test_count == 1
+        assert app.watcher_call_count == 1
         app.count -= 1
-        assert app.test_count == 0
+        assert app.watcher_call_count == 0
+
+
+async def test_watch_async_init_false():
+    """Ensure that async watchers are called eventually when set by user code"""
+
+    class WatchAsyncApp(App):
+        count = reactive(OLD_VALUE, init=False)
+        watcher_old_value = None
+        watcher_new_value = None
+        watcher_called_event = asyncio.Event()
+
+        async def watch_count(self, old_value: int, new_value: int) -> None:
+            self.watcher_old_value = old_value
+            self.watcher_new_value = new_value
+            self.watcher_called_event.set()
+
+    app = WatchAsyncApp()
+    async with app.run_test():
+        app.count = NEW_VALUE
+        assert app.count == NEW_VALUE  # Value is set immediately
+        try:
+            await asyncio.wait_for(app.watcher_called_event.wait(), timeout=0.05)
+        except TimeoutError:
+            pytest.fail("Async watch method (watch_count) wasn't called within timeout")
+
+        assert app.count == NEW_VALUE  # Sanity check
+        assert app.watcher_old_value == OLD_VALUE  # old_value passed to watch method
+        assert app.watcher_new_value == NEW_VALUE  # new_value passed to watch method
+
+
+async def test_watch_async_init_true():
+    """Ensure that when init is True in a reactive, its async watcher gets called
+    by Textual eventually, even when the user does not set the value themselves."""
+
+    class WatchAsyncApp(App):
+        count = reactive(OLD_VALUE, init=True)
+        watcher_called_event = asyncio.Event()
+        watcher_old_value = None
+        watcher_new_value = None
+
+        async def watch_count(self, old_value: int, new_value: int) -> None:
+            self.watcher_old_value = old_value
+            self.watcher_new_value = new_value
+            self.watcher_called_event.set()
+
+    app = WatchAsyncApp()
+    async with app.run_test():
+        try:
+            await asyncio.wait_for(app.watcher_called_event.wait(), timeout=0.05)
+        except TimeoutError:
+            pytest.fail("Async watcher wasn't called within timeout when reactive init = True")
+
+    assert app.count == OLD_VALUE
+    assert app.watcher_old_value == OLD_VALUE
+    assert app.watcher_new_value == OLD_VALUE  # The value wasn't changed
+
+
+@pytest.mark.xfail(reason="Reactive watcher is incorrectly always called the first time it is set, even if value is same [issue#1230]")
+async def test_watch_init_false_always_update_false():
+    class WatcherInitFalse(App):
+        count = reactive(0, init=False)
+        watcher_call_count = 0
+
+        def watch_count(self, new_value: int) -> None:
+            self.watcher_call_count += 1
+
+    app = WatcherInitFalse()
+    async with app.run_test():
+        app.count = 0  # Value hasn't changed, and always_update=False, so watch_count shouldn't run
+        assert app.watcher_call_count == 0
+
+
+async def test_watch_init_true():
+    class WatcherInitTrue(App):
+        count = var(OLD_VALUE)
+        watcher_call_count = 0
+
+        def watch_count(self, new_value: int) -> None:
+            self.watcher_call_count += 1
+
+    app = WatcherInitTrue()
+    async with app.run_test():
+        assert app.count == OLD_VALUE
+        assert app.watcher_call_count == 1  # Watcher called on init
+        app.count = NEW_VALUE  # User sets the value...
+        assert app.watcher_call_count == 2  # ...resulting in 2nd call
+        app.count = NEW_VALUE  # Setting to the SAME value
+        assert app.watcher_call_count == 2  # Watcher is NOT called again
+
+
+async def test_reactive_always_update():
+    calls = []
+
+    class AlwaysUpdate(App):
+        first_name = reactive("Darren", init=False, always_update=True)
+        last_name = reactive("Burns", init=False)
+
+        def watch_first_name(self, value):
+            calls.append(f"first_name {value}")
+
+        def watch_last_name(self, value):
+            calls.append(f"last_name {value}")
+
+    app = AlwaysUpdate()
+    async with app.run_test():
+        # Value is the same, but always_update=True, so watcher called...
+        app.first_name = "Darren"
+        assert calls == ["first_name Darren"]
+        # TODO: Commented out below due to issue#1230, should work after issue fixed
+        # Value is the same, and always_update=False, so watcher NOT called...
+        # app.last_name = "Burns"
+        # assert calls == ["first_name Darren"]
+        # Values changed, watch method always called regardless of always_update
+        app.first_name = "abc"
+        app.last_name = "def"
+        assert calls == ["first_name Darren", "first_name abc", "last_name def"]
+
+
+async def test_reactive_with_callable_default():
+    """A callable can be supplied as the default value for a reactive.
+    Textual will call it in order to retrieve the default value."""
+    called_with_app = None
+
+    def set_called(app: App) -> int:
+        nonlocal called_with_app
+        called_with_app = app
+        return OLD_VALUE
+
+    class ReactiveCallable(App):
+        value = reactive(set_called)
+        watcher_called_with = None
+
+        def watch_value(self, new_value):
+            self.watcher_called_with = new_value
+
+    app = ReactiveCallable()
+    async with app.run_test():
+        assert app.value == OLD_VALUE  # The value should be set to the return val of the callable
+    assert called_with_app is app  # Ensure the App is passed into the reactive default callable
+    assert app.watcher_called_with == OLD_VALUE
+
+
+@pytest.mark.xfail(reason="Validator methods not running when init=True [issue#1220]")
+async def test_validate_init_true():
+    """When init is True for a reactive attribute, Textual should call the validator
+    AND the watch method when the app starts."""
+
+    class ValidatorInitTrue(App):
+        count = var(5, init=True)
+
+        def validate_count(self, value: int) -> int:
+            return value + 1
+
+    app = ValidatorInitTrue()
+    async with app.run_test():
+        assert app.count == 6  # Validator should run, so value should be 5+1=6
+
+
+@pytest.mark.xfail(reason="Compute methods not called when init=True [issue#1227]")
+async def test_reactive_compute_first_time_set():
+    class ReactiveComputeFirstTimeSet(App):
+        number = reactive(1)
+        double_number = reactive(None)
+
+        def compute_double_number(self):
+            return self.number * 2
+
+    app = ReactiveComputeFirstTimeSet()
+    async with app.run_test():
+        await asyncio.sleep(.2)  # TODO: We sleep here while issue#1218 is open
+        assert app.double_number == 2
+
+
+@pytest.mark.xfail(reason="Compute methods not called immediately [issue#1218]")
+async def test_reactive_method_call_order():
+    class CallOrder(App):
+        count = reactive(OLD_VALUE, init=False)
+        count_times_ten = reactive(OLD_VALUE * 10)
+        calls = []
+
+        def validate_count(self, value: int) -> int:
+            self.calls.append(f"validate {value}")
+            return value + 1
+
+        def watch_count(self, value: int) -> None:
+            self.calls.append(f"watch {value}")
+
+        def compute_count_times_ten(self) -> int:
+            self.calls.append(f"compute {self.count}")
+            return self.count * 10
+
+    app = CallOrder()
+    async with app.run_test():
+        app.count = NEW_VALUE
+        assert app.calls == [
+            # The validator receives NEW_VALUE, since that's what the user
+            # set the reactive attribute to...
+            f"validate {NEW_VALUE}",
+            # The validator adds 1 to the new value, and this is what should
+            # be passed into the watcher...
+            f"watch {NEW_VALUE + 1}",
+            # The compute method accesses the reactive value directly, which
+            # should have been updated by the validator to NEW_VALUE + 1.
+            f"compute {NEW_VALUE + 1}",
+        ]
+        assert app.count == NEW_VALUE + 1
+        assert app.count_times_ten == (NEW_VALUE + 1) * 10