When comparing 2 numbers as "self.assertAlmostEqual(a, b, delta=1000)" the error message looks like this:    AssertionError: 27332885 != 27391120 within 1000 deltaEspecially when a and b are big numbers or differ a lot, it would be useful to see the absolute difference between the 2 numbers as in:    AssertionError: 27332885 != 27391120 within 1000 delta (58235 difference)

PR:https://github.com/python/cpython/pull/1331/

Is it worth to output a difference when the delta argument is not passed?Is it worth to output a signed difference rather than an absolute value?

Thanks for chiming in.> Is it worth to output a difference when the delta argument is not passed?Yes, probably. I will change that.> Is it worth to output a signed difference rather than an absolute value?Mmmm probably not IMHO. Personally I never care about the position of left and right arguments. I just want to check whether a and b are almost equal.

Done.

The patch looks good to me.

New changeset5d7a8d0c13737fd531b722ad76c505ef47aac96a by Giampaolo Rodola in branch 'master':bpo-30190: improved error msg for assertAlmostEqual(delta=...) (#1331)https://github.com/python/cpython/commit/5d7a8d0c13737fd531b722ad76c505ef47aac96a

New test produce deprecation warnings:/home/serhiy/py/cpython/Lib/unittest/test/test_assertions.py:228: DeprecationWarning: invalid escape sequence \(  ["^1 != 2 within 7 places \(1 difference\)$", "^oops$",/home/serhiy/py/cpython/Lib/unittest/test/test_assertions.py:229: DeprecationWarning: invalid escape sequence \(  "^1 != 2 within 7 places \(1 difference\)$",/home/serhiy/py/cpython/Lib/unittest/test/test_assertions.py:230: DeprecationWarning: invalid escape sequence \(  "^1 != 2 within 7 places \(1 difference\) : oops$"])

Mmm I can't see them. Am I supposed to enable this kind of warning somehow?

$ ./python -WaLib/unittest/test/test_assertions.pyLib/unittest/test/test_assertions.py:228: DeprecationWarning: invalid escape sequence \(  ["^1 != 2 within 7 places \(1 difference\)$", "^oops$",Lib/unittest/test/test_assertions.py:229: DeprecationWarning: invalid escape sequence \(  "^1 != 2 within 7 places \(1 difference\)$",Lib/unittest/test/test_assertions.py:230: DeprecationWarning: invalid escape sequence \(  "^1 != 2 within 7 places \(1 difference\) : oops$"])...................................----------------------------------------------------------------------Ran 35 tests in 0.052sOK

Warnings are not shown when the source is already compiled to .pyc file.$ find -name '*.py[co]' -exec rm '{}' +$ ./python -Wa -m test test_unittestRun tests sequentially0:00:00 load avg: 0.54 [1/1] test_unittest/home/serhiy/py/cpython/Lib/unittest/test/test_assertions.py:228: DeprecationWarning: invalid escape sequence \(  ["^1 != 2 within 7 places \(1 difference\)$", "^oops$",/home/serhiy/py/cpython/Lib/unittest/test/test_assertions.py:229: DeprecationWarning: invalid escape sequence \(  "^1 != 2 within 7 places \(1 difference\)$",/home/serhiy/py/cpython/Lib/unittest/test/test_assertions.py:230: DeprecationWarning: invalid escape sequence \(  "^1 != 2 within 7 places \(1 difference\) : oops$"])1 test OK.Total duration: 5 secTests result: SUCCESS

OK thanks. Fix coming.

Reopening as it needs backports for 2.7, 3.3, 3.4, 3.5 and 3.6.

Sorry, I accidentally picked up the wrong thread.