I like reading code, but even very nice code can be hard to follow without seeing what it does.

You can always enter a debugger to look at values during an execution, but that's annoying.

This package records values during execution, and shows them to you in an HTML page afterward.

Examples

Script Example

This runs the script at examples/loop.py while tracking values of expressions in that script:

seerun trackscript docs/examples/loop.html examples/loop.py

The HTML is here.

Module Example

This runs the script at examples/run_hypothesis.py while tracking expressions in a hypothesis-internal module I picked:

seerun trackmodule /Users/davidchudzicki/hypothesis-python/src/hypothesis/internal/conjecture/engine.py docs/examples/hypothesis.html --runscript examples/run_hypothesis.py

The HTML is here.

Here's the console output:

Falsifying example: test_one_of_filtered(x=4.0)
ERROR:root:`got exception executing tranformed tree
Traceback (most recent call last):
  File "/Users/davidchudzicki/seerun/seerun/run.py", line 108, in run
    **environment
  File "<string>", line 10, in <module>
  File "<string>", line 5, in test_one_of_filtered
  File "/Users/davidchudzicki/hypothesis-python/src/hypothesis/core.py", line 1052, in wrapped_test
    state.run()
  File "/Users/davidchudzicki/hypothesis-python/src/hypothesis/core.py", line 820, in run
    falsifying_example.__expected_traceback,
  File "/Users/davidchudzicki/hypothesis-python/src/hypothesis/core.py", line 581, in execute
    result = self.test_runner(data, run)
  File "/Users/davidchudzicki/hypothesis-python/src/hypothesis/executors.py", line 58, in default_new_style_executor
    return function(data)
  File "/Users/davidchudzicki/hypothesis-python/src/hypothesis/core.py", line 573, in run
    return test(*args, **kwargs)
  File "<string>", line 5, in test_one_of_filtered
  File "/Users/davidchudzicki/hypothesis-python/src/hypothesis/core.py", line 520, in test
    result = self.test(*args, **kwargs)
  File "<string>", line 7, in test_one_of_filtered
AssertionError

In this case, the log is showing us the expected exception. (Hypothesis raised AssertionError for the counterexample.)

The exception does not prevent the HTML output from being produced.

Development

Test coverage is 100%, except a bunch of pragma: no covers. The philosophy is that everything should either be covered or explicitly say it's not coveraged. (The uncovered stuff is either plausibly not worth the trouble, or much more embarrassingly, because I copied code I don't understand.)