214 lines
7.2 KiB
Python
214 lines
7.2 KiB
Python
"""Utilities for assertion debugging"""
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import py
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# The _reprcompare attribute on the util module is used by the new assertion
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# interpretation code and assertion rewriter to detect this plugin was
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# loaded and in turn call the hooks defined here as part of the
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# DebugInterpreter.
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_reprcompare = None
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def format_explanation(explanation):
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"""This formats an explanation
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Normally all embedded newlines are escaped, however there are
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three exceptions: \n{, \n} and \n~. The first two are intended
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cover nested explanations, see function and attribute explanations
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for examples (.visit_Call(), visit_Attribute()). The last one is
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for when one explanation needs to span multiple lines, e.g. when
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displaying diffs.
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"""
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# simplify 'assert False where False = ...'
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where = 0
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while True:
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start = where = explanation.find("False\n{False = ", where)
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if where == -1:
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break
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level = 0
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for i, c in enumerate(explanation[start:]):
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if c == "{":
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level += 1
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elif c == "}":
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level -= 1
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if not level:
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break
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else:
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raise AssertionError("unbalanced braces: %r" % (explanation,))
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end = start + i
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where = end
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if explanation[end - 1] == '\n':
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explanation = (explanation[:start] + explanation[start+15:end-1] +
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explanation[end+1:])
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where -= 17
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raw_lines = (explanation or '').split('\n')
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# escape newlines not followed by {, } and ~
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lines = [raw_lines[0]]
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for l in raw_lines[1:]:
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if l.startswith('{') or l.startswith('}') or l.startswith('~'):
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lines.append(l)
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else:
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lines[-1] += '\\n' + l
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result = lines[:1]
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stack = [0]
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stackcnt = [0]
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for line in lines[1:]:
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if line.startswith('{'):
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if stackcnt[-1]:
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s = 'and '
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else:
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s = 'where '
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stack.append(len(result))
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stackcnt[-1] += 1
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stackcnt.append(0)
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result.append(' +' + ' '*(len(stack)-1) + s + line[1:])
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elif line.startswith('}'):
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assert line.startswith('}')
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stack.pop()
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stackcnt.pop()
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result[stack[-1]] += line[1:]
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else:
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assert line.startswith('~')
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result.append(' '*len(stack) + line[1:])
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assert len(stack) == 1
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return '\n'.join(result)
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# Provide basestring in python3
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try:
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basestring = basestring
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except NameError:
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basestring = str
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def assertrepr_compare(op, left, right):
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"""return specialised explanations for some operators/operands"""
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width = 80 - 15 - len(op) - 2 # 15 chars indentation, 1 space around op
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left_repr = py.io.saferepr(left, maxsize=int(width/2))
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right_repr = py.io.saferepr(right, maxsize=width-len(left_repr))
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summary = '%s %s %s' % (left_repr, op, right_repr)
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issequence = lambda x: isinstance(x, (list, tuple))
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istext = lambda x: isinstance(x, basestring)
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isdict = lambda x: isinstance(x, dict)
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isset = lambda x: isinstance(x, set)
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explanation = None
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try:
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if op == '==':
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if istext(left) and istext(right):
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explanation = _diff_text(left, right)
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elif issequence(left) and issequence(right):
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explanation = _compare_eq_sequence(left, right)
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elif isset(left) and isset(right):
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explanation = _compare_eq_set(left, right)
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elif isdict(left) and isdict(right):
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explanation = _diff_text(py.std.pprint.pformat(left),
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py.std.pprint.pformat(right))
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elif op == 'not in':
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if istext(left) and istext(right):
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explanation = _notin_text(left, right)
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except py.builtin._sysex:
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raise
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except:
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excinfo = py.code.ExceptionInfo()
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explanation = ['(pytest_assertion plugin: representation of '
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'details failed. Probably an object has a faulty __repr__.)',
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str(excinfo)
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]
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if not explanation:
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return None
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# Don't include pageloads of data, should be configurable
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if len(''.join(explanation)) > 80*8:
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explanation = ['Detailed information too verbose, truncated']
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return [summary] + explanation
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def _diff_text(left, right):
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"""Return the explanation for the diff between text
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This will skip leading and trailing characters which are
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identical to keep the diff minimal.
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"""
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explanation = []
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i = 0 # just in case left or right has zero length
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for i in range(min(len(left), len(right))):
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if left[i] != right[i]:
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break
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if i > 42:
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i -= 10 # Provide some context
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explanation = ['Skipping %s identical '
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'leading characters in diff' % i]
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left = left[i:]
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right = right[i:]
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if len(left) == len(right):
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for i in range(len(left)):
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if left[-i] != right[-i]:
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break
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if i > 42:
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i -= 10 # Provide some context
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explanation += ['Skipping %s identical '
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'trailing characters in diff' % i]
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left = left[:-i]
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right = right[:-i]
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explanation += [line.strip('\n')
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for line in py.std.difflib.ndiff(left.splitlines(),
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right.splitlines())]
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return explanation
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def _compare_eq_sequence(left, right):
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explanation = []
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for i in range(min(len(left), len(right))):
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if left[i] != right[i]:
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explanation += ['At index %s diff: %r != %r' %
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(i, left[i], right[i])]
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break
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if len(left) > len(right):
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explanation += ['Left contains more items, '
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'first extra item: %s' % py.io.saferepr(left[len(right)],)]
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elif len(left) < len(right):
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explanation += ['Right contains more items, '
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'first extra item: %s' % py.io.saferepr(right[len(left)],)]
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return explanation # + _diff_text(py.std.pprint.pformat(left),
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# py.std.pprint.pformat(right))
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def _compare_eq_set(left, right):
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explanation = []
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diff_left = left - right
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diff_right = right - left
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if diff_left:
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explanation.append('Extra items in the left set:')
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for item in diff_left:
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explanation.append(py.io.saferepr(item))
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if diff_right:
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explanation.append('Extra items in the right set:')
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for item in diff_right:
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explanation.append(py.io.saferepr(item))
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return explanation
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def _notin_text(term, text):
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index = text.find(term)
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head = text[:index]
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tail = text[index+len(term):]
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correct_text = head + tail
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diff = _diff_text(correct_text, text)
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newdiff = ['%s is contained here:' % py.io.saferepr(term, maxsize=42)]
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for line in diff:
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if line.startswith('Skipping'):
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continue
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if line.startswith('- '):
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continue
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if line.startswith('+ '):
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newdiff.append(' ' + line[2:])
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else:
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newdiff.append(line)
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return newdiff
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