TestCase.flushWarnings shouldn't use source files to implement its "offendingFunctions" feature

[twisted-trac]

	@exarkun reported
Trac ID	trac#3598
Type	defect
Created	2009-01-04 00:37:52Z
Branch	https://github.com/twisted/twisted/tree/findlinestarts-3598

Using source files to determine which function a warning was emitted from is unreliable. It fails if:

1. The source file is missing
2. The source file is out of date with the bytecode file
3. It's kind of slow

dis.findlinestarts can provide the necessary information and is now public.

Searchable metadata

``` trac-id__3598 3598 type__defect defect reporter__exarkun exarkun priority__high high milestone__ branch__branches_findlinestarts_3598 branches/findlinestarts-3598 branch_author__exarkun exarkun status__closed closed resolution__fixed fixed component__trial trial keywords__ time__1231029472000000 1231029472000000 changetime__1232114755000000 1232114755000000 version__None None owner__ ```

[twisted-trac]

	@exarkun removed owner

Think this is in good shape now.

[twisted-trac]

	@radix set owner to @exarkun

[1] Need to mention copyright of that code copied from Python

[2] in test_renamedSource:

• a: you should not call the original filename "renamedsourcefile", since that is confusing.
• b: I don't think this comment is correct:

  • Drop it from memory so we can import it again later

You don't actually need to drop it so you can import it again, since it's going to be imported with the different name, right? Of course, you do need to clean it up, but you can do that at the end.

[3] Please change that function to not use single-letter variables that are used across more than one line.

[4] I don't know whether the following expression has off-by-one errors:

• if not (first <= w.lineno <= last):

Can you please add tests for all of the edge cases, thank you.

[twisted-trac]

	@exarkun removed owner

All points addressed, I think. Build results: http://buildbot.twistedmatrix.com/boxes-supported?branch=/branches/findlinestarts-3598

[twisted-trac]

	@mwhudson set owner to @exarkun

I think it looks fine. I have two small comments.

1. Saying "inspect.getabsfile(aFunction) returns bad results sometimes." is a bit useless. What are bad results? When does it generate them?

2. I know you apologise for it, but 'renamedsourcefile.py' is never actually renamed. I think something plain 'module.py' would be clearer.

These are minor enough that I don't want to review this again :) Please fix and land.

[twisted-trac]

	Automation removed owner

[twisted-trac]

	@exarkun set status to closed

(In [26043]) Merge findlinestarts-3598

Author: exarkun Reviewer: radix, mwhudson Fixes: #3598

Change the implementation of twisted.trial.unittest.TestCase.flushWarnings so that it works properly when a warning is emitted from a module which is defined by a source file which has been renamed since it was compiled. Previously, the rename would cause file names to disagree in certain places and prevent warnings emitted from code in a renamed file from being flushed.

[twisted-trac]

	@exarkun commented

(In [25848]) add/adjust comments in new test method to be more descriptive/accurate

refs #3598

[twisted-trac]

	@exarkun commented

(In [25849]) document copyright holder and license of _findlinestarts

refs #3598

[twisted-trac]

	@exarkun commented

(In [25781]) Branching to 'findlinestarts-3598'

[twisted-trac]

	@exarkun commented

(In [25782]) use dis.findlinestarts instead of inspect.getsourcelines

refs #3598

[twisted-trac]

	@exarkun commented

(In [25846]) test edge cases for line number stuff

refs #3598

[twisted-trac]

	@exarkun commented

(In [25847]) rename single letter variable "w" to something more descriptive

refs #3598

[twisted-trac]

	@exarkun commented

This is a small part of #3554.

[twisted-trac]

	@exarkun commented

(In [26041]) explain the getabsfile problem in more detail; change the name of the module used in the renamed-source-file-test to be more clear

refs #3598