I have a few tests which do imports from all kinds of places and despite passing, they may cause

coverage.py

to trip. I wouldn’t post it here given it’s a pure

coverage.py

problem, but the path looks dodgy having

(builtin)

which looks like some variable expansion / string interpolation issue? Have seen Eric had problems with https://github.com/pantsbuild/pants/pull/11129, not sure if that’s relevant or not. It feels wrong that

(builtin)

is in the constructed path. Ignoring errors when generating coverage HTML reports (https://coverage.readthedocs.io/en/coverage-5.5/config.html#report --

ignore_errors

) works fine and the results look sensible.

I confirm that I’ve copied/pasted the output without any editing

pants_version = "2.5.1rc3"

and tried on

pants_version = "2.5.1"

the shims contents is standard, what it used to be really

so this path

(builtin)

has been collected into the

.coverage

file and of course when producing report it can’t find it

Found it 🙂 PySide2 is guilty, it seems! You should be able to reproduce it on a example-python repo (https://github.com/pantsbuild/example-python) by adding a few lines of code:

diff --git a/BUILD b/BUILD
index 9c0a8bc..9e6a482 100644
--- a/BUILD
+++ b/BUILD
@@ -20,5 +20,7 @@ python_requirements(
   module_mapping={
     "ansicolors": ["colors"],
     "setuptools": ["pkg_resources"],
+    "PySide2": ["PySide2"],
+
   },
 )
diff --git a/helloworld/greet/greeting_test.py b/helloworld/greet/greeting_test.py
index 4faa9e8..7e6de79 100644
--- a/helloworld/greet/greeting_test.py
+++ b/helloworld/greet/greeting_test.py
@@ -3,6 +3,7 @@
 
 from helloworld.greet.greeting import Greeter
 
+from PySide2.QtWidgets import QApplication
 
 def test_greeter() -> None:
     greeter = Greeter(languages=["es"], greetings=["good morning"])
diff --git a/pants.toml b/pants.toml
index b5ee007..b5a06bb 100644
--- a/pants.toml
+++ b/pants.toml
@@ -36,3 +36,9 @@ interpreter_search_paths = ["<PATH>", "<PYENV>"]
 # See <https://www.pantsbuild.org/docs/protobuf>.
 runtime_dependencies = ["//:protobuf"]
 mypy_plugin = true
+
+[test]
+use_coverage = true
+
+[coverage-py]
+report = ["html"]
diff --git a/requirements.txt b/requirements.txt
index ffab1be..f11aee9 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -5,3 +5,4 @@ ansicolors>=1.0.2
 setuptools<54.0,>=50.3.0
 translate>=3.2.1
 protobuf>=3.11.3
+PySide2

I am back 🙂 so it turns out that

coverage.py

runs the code with PySide2 just fine and it looks like Pants may be doing something that causes coverage to be confused with the paths. 😞 I’ve authored a minimal repro in a public GitHub repo — https://github.com/alexey-tereshenkov-oxb/monorepo-coverage-pants. It showcases how

coverage.py

works and how Pants fails. I’ll make

coverage.py

ignore the errors to be able to go on with my life, but thought it may be worth sharing with you the repo in case you’d ever want to step through what Pants is doing on the minimal monorepo. @hundreds-father-404