diff --git a/sandbox/uber.py b/sandbox/uber.py
index 1d04834c2..026447573 100644
--- a/sandbox/uber.py
+++ b/sandbox/uber.py
@@ -1,9 +1,7 @@
-import time
-
-from textual.app import App
 from textual import events
-from textual.widgets import Placeholder
+from textual.app import App
 from textual.widget import Widget
+from textual.widgets import Placeholder
 
 
 class BasicApp(App):
diff --git a/src/textual/devtools/redirect_output.py b/src/textual/devtools/redirect_output.py
index ce8ae9208..6b0381b8e 100644
--- a/src/textual/devtools/redirect_output.py
+++ b/src/textual/devtools/redirect_output.py
@@ -51,10 +51,9 @@ class DevtoolsRedirector:
         """
         log_batch: list[DevtoolsLog] = []
         for log in self._buffer:
-            end_of_batch = (
-                log_batch
-                and log_batch[-1].caller.filename != log.caller.filename
-                and log_batch[-1].caller.lineno != log.caller.lineno
+            end_of_batch = log_batch and (
+                log_batch[-1].caller.filename != log.caller.filename
+                or log_batch[-1].caller.lineno != log.caller.lineno
             )
             if end_of_batch:
                 self._log_batched(log_batch)
diff --git a/tests/devtools/__init__.py b/tests/devtools/__init__.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/tests/test_devtools.py b/tests/devtools/test_devtools.py
similarity index 100%
rename from tests/test_devtools.py
rename to tests/devtools/test_devtools.py
diff --git a/tests/test_devtools_client.py b/tests/devtools/test_devtools_client.py
similarity index 97%
rename from tests/test_devtools_client.py
rename to tests/devtools/test_devtools_client.py
index 0bdcbfa61..9b1617e03 100644
--- a/tests/test_devtools_client.py
+++ b/tests/devtools/test_devtools_client.py
@@ -90,7 +90,9 @@ async def test_devtools_client_update_console_dimensions(devtools, server):
     """Sending new server info through websocket from server to client should (eventually)
     result in the dimensions of the devtools client console being updated to match.
     """
-    server_to_client: WebSocketResponse = next(iter(server.app["service"].clients)).websocket
+    server_to_client: WebSocketResponse = next(
+        iter(server.app["service"].clients)
+    ).websocket
     server_info = {
         "type": "server_info",
         "payload": {
diff --git a/tests/devtools/test_redirect_output.py b/tests/devtools/test_redirect_output.py
new file mode 100644
index 000000000..d53f0345d
--- /dev/null
+++ b/tests/devtools/test_redirect_output.py
@@ -0,0 +1,116 @@
+import json
+import pprint
+from contextlib import redirect_stdout
+from datetime import datetime
+
+import time_machine
+
+from textual.devtools.redirect_output import DevtoolsRedirector
+
+TIMESTAMP = 1649166819
+
+
+@time_machine.travel(datetime.fromtimestamp(TIMESTAMP))
+async def test_print_is_redirected_to_devtools(devtools):
+    await devtools._stop_log_queue_processing()
+
+    with redirect_stdout(DevtoolsRedirector(devtools)):
+        print("Hello, world!")
+
+    assert devtools.log_queue.qsize() == 1
+
+    queued_log = await devtools.log_queue.get()
+    queued_log_json = json.loads(queued_log)
+    payload = queued_log_json["payload"]
+
+    assert queued_log_json["type"] == "client_log"
+    assert payload["timestamp"] == TIMESTAMP
+    assert (
+            payload["encoded_segments"]
+            == "gANdcQAoY3JpY2guc2VnbWVudApTZWdtZW50CnEBWA0AAABIZWxsbywgd29ybGQhcQJOTodxA4FxBGgBWAEAAAAKcQVOTodxBoFxB2Uu"
+    )
+
+
+@time_machine.travel(datetime.fromtimestamp(TIMESTAMP))
+async def test_print_without_flush_not_sent_to_devtools(devtools):
+    await devtools._stop_log_queue_processing()
+
+    with redirect_stdout(DevtoolsRedirector(devtools)):
+        # End is no longer newline character, so print will no longer
+        # flush the output buffer by default.
+        print("Hello, world!", end="")
+
+    assert devtools.log_queue.qsize() == 0
+
+
+@time_machine.travel(datetime.fromtimestamp(TIMESTAMP))
+async def test_print_forced_flush_sent_to_devtools(devtools):
+    await devtools._stop_log_queue_processing()
+
+    with redirect_stdout(DevtoolsRedirector(devtools)):
+        print("Hello, world!", end="", flush=True)
+
+    assert devtools.log_queue.qsize() == 1
+
+
+@time_machine.travel(datetime.fromtimestamp(TIMESTAMP))
+async def test_print_multiple_args_batched_as_one_log(devtools):
+    await devtools._stop_log_queue_processing()
+
+    with redirect_stdout(DevtoolsRedirector(devtools)):
+        # We call print with multiple arguments here, but it
+        # results in a single log added to the log queue.
+        print("Hello", "world", "multiple")
+
+    assert devtools.log_queue.qsize() == 1
+
+    queued_log = await devtools.log_queue.get()
+    queued_log_json = json.loads(queued_log)
+    payload = queued_log_json["payload"]
+
+    assert queued_log_json["type"] == "client_log"
+    assert payload["timestamp"] == TIMESTAMP
+    assert payload[
+               "encoded_segments"] == "gANdcQAoY3JpY2guc2VnbWVudApTZWdtZW50CnEBWBQAAABIZWxsbyB3b3JsZCBtdWx0aXBsZXECTk6HcQOBcQRoAVgBAAAACnEFTk6HcQaBcQdlLg=="
+    assert len(payload["path"]) > 0
+    assert payload["line_number"] != 0
+
+
+@time_machine.travel(datetime.fromtimestamp(TIMESTAMP))
+async def test_print_multiple_args_batched_as_one_log(devtools):
+    await devtools._stop_log_queue_processing()
+    redirector = DevtoolsRedirector(devtools)
+    with redirect_stdout(redirector):
+        # This print adds 3 messages to the buffer that can be batched
+        print("The first", "batch", "of logs", end="")
+        # This message cannot be batched with the previous message,
+        # and so it will be the 2nd item added to the log queue.
+        print("I'm in the second batch")
+
+    assert devtools.log_queue.qsize() == 2
+
+
+@time_machine.travel(datetime.fromtimestamp(TIMESTAMP))
+async def test_print_strings_containing_newline_flushed(devtools):
+    await devtools._stop_log_queue_processing()
+
+    with redirect_stdout(DevtoolsRedirector(devtools)):
+        # Flushing is disabled since end="", but the first
+        # string will be flushed since it contains a newline
+        print("Hel\nlo", end="")
+        print("world", end="")
+
+    assert devtools.log_queue.qsize() == 1
+
+
+@time_machine.travel(datetime.fromtimestamp(TIMESTAMP))
+async def test_flush_flushes_buffered_logs(devtools):
+    await devtools._stop_log_queue_processing()
+
+    redirector = DevtoolsRedirector(devtools)
+    with redirect_stdout(redirector):
+        print("x", end="")
+
+    assert devtools.log_queue.qsize() == 0
+    redirector.flush()
+    assert devtools.log_queue.qsize() == 1