Move the current Input tests into a subdirectory

I'm going to be adding more tests for Input, and I don't want to be doing
one large monolithic file of them, so this makes a space where
Input-targeting tests can live together and be easy to spot.

tests/input/test_input_value_visibility.py

@@ -0,0 +1,101 @@
+from rich.console import Console
+from textual.app import App
+from textual.widgets import Input
+
+
+async def test_input_value_visible_on_instantiation():
+    """Check if the full input value is rendered if the input is instantiated with it."""
+
+    class MyApp(App):
+        def compose(self):
+            yield Input(value="value")
+
+    app = MyApp()
+    async with app.run_test():
+        console = Console(width=5)
+        with console.capture() as capture:
+            console.print(app.query_one(Input).render())
+        assert capture.get() == "value"
+
+
+async def test_input_value_visible_after_value_assignment():
+    """Check if the full input value is rendered if the value is assigned to programmatically."""
+
+    class MyApp(App):
+        def compose(self):
+            yield Input()
+
+        def on_mount(self):
+            self.query_one(Input).value = "value"
+
+    app = MyApp()
+    async with app.run_test():
+        console = Console(width=5)
+        with console.capture() as capture:
+            console.print(app.query_one(Input).render())
+        assert capture.get() == "value"
+
+
+async def test_input_value_visible_if_mounted_later():
+    """Check if full input value is rendered if the widget is mounted later."""
+
+    class MyApp(App):
+        BINDINGS = [("a", "add_input", "add_input")]
+
+        async def action_add_input(self):
+            await self.mount(Input(value="value"))
+
+    app = MyApp()
+    async with app.run_test() as pilot:
+        await pilot.press("a")
+        await pilot.pause()
+        console = Console(width=5)
+        with console.capture() as capture:
+            console.print(app.query_one(Input).render())
+        assert capture.get() == "value"
+
+
+async def test_input_value_visible_if_mounted_later_and_focused():
+    """Check if full input value is rendered if the widget is mounted later and immediately focused."""
+
+    class MyApp(App):
+        BINDINGS = [("a", "add_input", "add_input")]
+
+        async def action_add_input(self):
+            inp = Input(value="value")
+            await self.mount(inp)
+            inp.focus()
+
+    app = MyApp()
+    async with app.run_test() as pilot:
+        await pilot.press("a")
+        await pilot.pause()
+        console = Console(width=5)
+        with console.capture() as capture:
+            console.print(app.query_one(Input).render())
+        assert capture.get() == "value"
+
+
+async def test_input_value_visible_if_mounted_later_and_assigned_after():
+    """Check if full value rendered if the widget is mounted later and the value is then assigned to."""
+
+    class MyApp(App):
+        BINDINGS = [
+            ("a", "add_input", "add_input"),
+            ("v", "set_value", "set_value"),
+        ]
+
+        async def action_add_input(self):
+            await self.mount(Input())
+
+        def action_set_value(self):
+            self.query_one(Input).value = "value"
+
+    app = MyApp()
+    async with app.run_test() as pilot:
+        await pilot.press("a")
+        await pilot.press("v")
+        console = Console(width=5)
+        with console.capture() as capture:
+            console.print(app.query_one(Input).render())
+        assert capture.get() == "value"