return an error if the explicitly specified config is missing

[rkm]

fixes #1497

[sigmavirus24]

This is unrelated to your change. Please revert it

[rkm]

Without changing the two assertions, the output is:

$ flake8 --config foo.cfg t.py
There was a critical error during execution of Flake8:
The specified config file does not exist: foo.cfg
Traceback (most recent call last):
  File "/home/rkm/dev/pycqa/flake8/venv/bin/flake8", line 33, in <module>
    sys.exit(load_entry_point('flake8', 'console_scripts', 'flake8')())
  File "/home/rkm/dev/pycqa/flake8/src/flake8/main/cli.py", line 22, in main
    app.run(argv)
  File "/home/rkm/dev/pycqa/flake8/src/flake8/main/application.py", line 395, in run
    assert self.options is not None
AssertionError

Compared to simply:

$ flake8 --config foo.cfg t.py
There was a critical error during execution of Flake8:
The specified config file does not exist: foo.cfg

To me the traceback seems misleading, since it doesn't point to the actual call site. If that's acceptable then I can re-add the assertions, otherwise let me know if you have a better solution in mind.

[asottile]

I think this should be

    def exit_code(self) -> int:
        """Return the program exit code."""
        if self.catastrophic_failure:
            return 1
        assert self.options is not None
        if self.options.exit_zero:
            return 0
        else:
            return int(self.result_count > 0) 

eventually I want to factor away the Application class since the lateinit nullable attributes pose a lot of problems and we have to side-step the typechecker a lot

[asottile]

actually it's slightly more involved -- here's a fix for that:

diff --git a/src/flake8/main/application.py b/src/flake8/main/application.py
index ee46f6a..1894881 100644
--- a/src/flake8/main/application.py
+++ b/src/flake8/main/application.py
@@ -115,10 +115,13 @@ class Application:
 
     def exit_code(self) -> int:
         """Return the program exit code."""
-        if self.options and self.options.exit_zero:
-            return int(self.catastrophic_failure)
+        if self.catastrophic_failure:
+            return 1
+        assert self.options is not None
+        if self.options.exit_zero:
+            return 0
         else:
-            return int((self.result_count > 0) or self.catastrophic_failure)
+            return int(self.result_count > 0)
 
     def find_plugins(
         self,
@@ -390,6 +393,7 @@ class Application:
         except exceptions.EarlyQuit:
             self.catastrophic_failure = True
             print("... stopped while processing files")
-
-        if self.options and self.options.count:
-            print(self.result_count)
+        else:
+            assert self.options is not None
+            if self.options.count:
+                print(self.result_count)

actually, I think this is broken on main so I'll split it out to a separate patch

[sigmavirus24]

Why wouldn't you include the config value in the exception?

[rkm]

have added this now

[sigmavirus24]

We have not documented that we would raise an error if the configuration file doesn't exist and if we wanted to split hairs, this is backwards incompatible behaviour meaning we couldn't easily just accept this at the moment

[rkm]

Thanks for reviewing. I hadn't considered there would be any worries about backwards incompatibility. Feel free to close this if you think that's a blocker. If so then could we at least update the docs to indicate the existing behaviour?

[asottile]

while this ~technically breaks backward compatibility -- I think this is a move in the right direction and I'm ok with this being a new error

just needs a slight rebase though 👍

[asottile]