From 9569a98c7788bd9f433d0590ee621230c50d906c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rodrigo=20Gir=C3=A3o=20Serr=C3=A3o?=
 <5621605+rodrigogiraoserrao@users.noreply.github.com>
Date: Mon, 29 May 2023 19:49:58 +0100
Subject: [PATCH] Increase worker coverage and fix bug.

---
 CHANGELOG.md          |  1 +
 src/textual/worker.py |  2 +-
 tests/test_worker.py  | 62 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 64 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5cc55decb..a98498540 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 - Fixed zero division error https://github.com/Textualize/textual/issues/2673
 - Fix `scroll_to_center` when there were nested layers out of view (Compositor full_map not populated fully) https://github.com/Textualize/textual/pull/2684
+- Issue with computing progress in workers https://github.com/Textualize/textual/pull/2686
 
 ### Added
 
diff --git a/src/textual/worker.py b/src/textual/worker.py
index 68b11bc95..de4295a8a 100644
--- a/src/textual/worker.py
+++ b/src/textual/worker.py
@@ -256,7 +256,7 @@ class Worker(Generic[ResultType]):
         if completed_steps is not None:
             self._completed_steps += completed_steps
         if total_steps != -1:
-            self._total_steps = None if total_steps is None else min(0, total_steps)
+            self._total_steps = None if total_steps is None else max(0, total_steps)
 
     def advance(self, steps: int = 1) -> None:
         """Advance the number of completed steps.
diff --git a/tests/test_worker.py b/tests/test_worker.py
index 3ef802f5f..f3c6dc239 100644
--- a/tests/test_worker.py
+++ b/tests/test_worker.py
@@ -1,11 +1,15 @@
 import asyncio
+from re import A
 
 import pytest
 
 from textual.app import App
 from textual.worker import (
+    DeadlockError,
+    NoActiveWorker,
     Worker,
     WorkerCancelled,
+    WorkerError,
     WorkerFailed,
     WorkerState,
     get_current_worker,
@@ -153,3 +157,61 @@ async def test_get_worker() -> None:
         worker._start(app)
 
         assert await worker.wait() is worker
+
+
+def test_no_active_worker() -> None:
+    """No active worker raises a specific exception."""
+    with pytest.raises(NoActiveWorker):
+        get_current_worker()
+
+
+async def test_progress_update():
+    async def long_work():
+        pass
+
+    app = App()
+    async with app.run_test():
+        worker = Worker(app, long_work)
+        worker._start(app)
+        worker.update(total_steps=100)
+        assert worker.progress == 0
+        worker.advance(50)
+        assert worker.progress == 50
+        worker.update(completed_steps=23)
+        assert worker.progress == 73
+
+
+async def test_double_start():
+    async def long_work():
+        return 0
+
+    app = App()
+    async with app.run_test():
+        worker = Worker(app, long_work)
+        worker._start(app)
+        worker._start(app)
+        assert await worker.wait() == 0
+
+
+async def test_self_referential_deadlock():
+    async def self_referential_work():
+        await get_current_worker().wait()
+
+    app = App()
+    async with app.run_test():
+        worker = Worker(app, self_referential_work)
+        worker._start(app)
+        with pytest.raises(WorkerFailed) as exc:
+            await worker.wait()
+            assert exc.type is DeadlockError
+
+
+async def test_wait_without_start():
+    async def work():
+        return
+
+    app = App()
+    async with app.run_test():
+        worker = Worker(app, work)
+        with pytest.raises(WorkerError):
+            await worker.wait()