Coverage not working with mypy ignores and vague errors

[Lyranile]

Bug Report

(A clear and concise description of what the bug is.)
Coverage not showing the same result as mypy

To Reproduce

class A(BaseModel):
   b: str = Field(default=..., description="some var")

Expected Behavior
To get the code coverage based on what I get with the mypy src call

Actual Behavior

I'm getting low coverage despite mypy not complaining after these ignores
Ignore missing imports and no warn unused ignores just doesnt apply to coverage, it shows passed when using mypy src but fails on coverage

Your Environment

• Mypy version used: latest
• Mypy command-line flags: mypy
  --disallow-untyped-calls
  --disallow-untyped-defs
  --check-untyped-defs
  --follow-imports=normal
  --explicit-package-bases
  --allow-untyped-globals
  --ignore-missing-imports
  --no-warn-unused-ignores
  --warn-return-any
  .
• Mypy configuration options from mypy.ini (and other config files):
• Python version used: 3.13.2

[sterliakov]

I struggle to understand your problem, perhaps it's just me, but could you explain the issue somewhat more clearly?

There are no ignores in your code, but there are unresolved symbols (presumably BaseModel and Field come from pydantic, but you don't mention enabling pydantic plugin).

And what does coverage have to do with this? If you're talking about coverage.py, then it measures runtime code coverage by tests, and mypy does not run any code, it's a static type checker that parses code to AST and performs in-depth analysis relying on type hints/annotations. It does not execute your python code. If your test coverage is low, you probably need to write more tests?..

mypy can also provide some reports on annotation coverage - how much of your code is missing annotations, how often Any appears, etc, you can read about these features in documentation.

[Lyranile]

My question in short is that mypy src is different than what mypy --xml-report or --html-report
Why is that and how can I make mypy warn me from what the report warns me on

[sterliakov]

--html-report flag

Causes mypy to generate an HTML type checking coverage report.

So yes, it does not produce the same information as mypy run itself. Those represent different concepts: mypy invocation lists errors detected in your code, while the HTML/XML report shows how much of your code is covered with annotations.

If you want mypy to fail when annotations are missing, there are other configuration flags - for example, disallow_untyped_defs to reject any functions with missing annotations. If you want to treat only "red" table lines (>20% uncovered?) as "warns", then there's no such functionality AFAIC - you can only require all functions to be annotated.

[sterliakov]

Ah, I get it now. There are several methods attached to the line of class' def - __init__, __mypy-replace and __replace__ - coming from dataclass_transform of a BaseModel. Those are plugin-generated - perhaps they should be excluded from reports or analyzed a bit differently. If I enable pydantic plugin, this changes, but to arguably even worse outcome (the yellow line turns red). Here's what the report body looks like (same but yellow with plugin disabled):

Thanks for letting us know!