How to run a single Python unittest.TestCase test in VIM?

Question

I have two simple Python tests in my_tests.py file:

from unittest import TestCase

class MyTestCase(TestCase):
    def test_true(self):
        self.assertTrue(True)

    def test_false(self):
        self.assertFalse(True)

which can be executed using pytest my_tests.py.

I want to write VIM shortcut, which would execute one test on which the cursor is on. For example, the shortcut could call: :!pytest my_tests.py::MyTestCase::test_false<CR>.

My question is how to get current filename, Python class name and Python method name on which the cursor is, which are needed for the shortcut.

Answer 1

Here's a pure vimscript function that builds up the command by searching for functions (def) and classes (class). You may need to adjust the filename modifiers or the command; parameters or global vars could be used for that if one wanted to build a plugin.

" ~/.vim/autoload/python.vim

function python#runTest() abort
  const l:file = expand('%:p')
  if empty(l:file)
    return
  else
    const l:func = search('^\s*def', 'bcnW')->getline()
          \ ->substitute('^\s*def\s*\(\k*\).*', '\1', '')
    const l:class = search('^\s*class', 'bcnW')->getline()
          \ ->substitute('^\s*class\s*\(\k*\).*', '\1', '')
    const l:cmd = printf('!pytest %s%s%s',
          \ l:file,
          \ (empty(l:class) ? '' : '::'.l:class),
          \ (empty(l:func) ? '' : '::'.l:func))
    execute l:cmd
  endif
endfunction

Then you could put a mapping in ~/.vim/after/ftplugin/python.vim like

nnoremap <buffer> <localleader>t :call python#runTest()<CR>

Answer 2

I have managed to automate this feature using vimscript-python. Add this function to your ~/.vimrc:

function! RunCurrentPythonTest()
python3 << EOF

import re
import vim  # https://vimhelp.org/if_pyth.txt.html

cursor = vim.current.window.cursor
test_filename = vim.eval("expand('%p')")

test_name = None
class_name = None
for line_no in range(cursor[0]-1, -1, -1):
    line = vim.current.buffer[line_no]
    if not test_name and line.lstrip().startswith('def test'):
        test_name = re.findall('def (\w+)\(', line)[0]
    if not class_name and line.startswith('class'):
        class_name = re.findall('class (\w+)\(', line)[0]
        break

cmd = f'!pytest {test_filename}'
if class_name:
    cmd += f'::{class_name}'
if test_name:
    cmd += f'::{test_name}'
vim.command(cmd)

EOF
endfunction

And map this function to ;t:

map     ;t          :call RunCurrentPythonTest()<CR>

Hover on a Python test, press ;t and great success - only that one test is executed:

================================================================== FAILURES ===================================================================
____________________________________________________________ MyTestCase.test_false ____________________________________________________________

self = <my_tests.MyTestCase testMethod=test_false>

    def test_false(self):
>       self.assertFalse(True)
E       AssertionError: True is not false

bin/my_tests.py:9: AssertionError
============================================================== 1 failed in 0.04s ==============================================================

This implementation has additional feature: If you hover on a TestCase definition line - whole test case will be executed. And if you navigate to the begging of the file - all tests of the file will be executed.