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Jython is an implementation of the high-level, dynamic, object-oriented
language Python written in 100% Pure Java, and seamlessly integrated with
the Java platform. It thus allows you to run Python on any Java platform.
# Tracing in Jython works somewhat similarly to CPython, with the following exceptions:
#
# - No support for jump. Can't do that without dynamic bytecode
# rewriting OR at least until we support a Python bytecode
# interpreter
#
# - Some differences in how we compile, which results in different
# trace orders. This is of course an implementation detail. For
# example, we do not bother to dead-code while 0: loops because the
# JVM does a good job of that (and more aggressively than CPython
# for example, it should be to see comparable things like while
# False).
#
# - Related to this, we record f.setlineno in too many places in our
# code and not at all in the try, since this doesn't correspond to a
# bytecode on the JVM. The latter records events separately.
#
# Testing the line trace facility.
from test import test_support
import unittest
import sys
import difflib
# A very basic example. If this fails, we're in deep trouble.
def basic():
return 1
basic.events = [(0, 'call'),
(1, 'line'),
(1, 'return')]
# Many of the tests below are tricky because they involve pass statements.
# If there is implicit control flow around a pass statement (in an except
# clause or else caluse) under what conditions do you set a line number
# following that clause?
# The entire "while 0:" statement is optimized away. No code
# exists for it, so the line numbers skip directly from "del x"
# to "x = 1".
def arigo_example():
x = 1
del x
while 0:
pass
x = 1
arigo_example.events = [(0, 'call'),
(1, 'line'),
(2, 'line'),
(5, 'line'),
(5, 'return')]
# check that lines consisting of just one instruction get traced:
def one_instr_line():
x = 1
del x
x = 1
one_instr_line.events = [(0, 'call'),
(1, 'line'),
(2, 'line'),
(3, 'line'),
(3, 'return')]
def no_pop_tops(): # 0
x = 1 # 1
for a in range(2): # 2
if a: # 3
x = 1 # 4
else: # 5
x = 1 # 6
no_pop_tops.events = [(0, 'call'),
(1, 'line'),
(2, 'line'),
(3, 'line'),
(6, 'line'),
(2, 'line'),
(3, 'line'),
(4, 'line'),
(2, 'line'),
(2, 'return')]
def no_pop_blocks():
y = 1
while not y:
bla
x = 1
no_pop_blocks.events = [(0, 'call'),
(1, 'line'),
(2, 'line'),
(4, 'line'),
(4, 'return')]
def called(): # line -3
x = 1
def call(): # line 0
called()
call.events = [(0, 'call'),
(1, 'line'),
(-3, 'call'),
(-2, 'line'),
(-2, 'return'),
(1, 'return')]
def raises():
raise Exception
def test_raise():
try:
raises()
except Exception, exc:
x = 1
test_raise.events = [(0, 'call'),
(1, 'line'),
(2, 'line'),
(-3, 'call'),
(-2, 'line'),
(-2, 'exception'),
(-2, 'return'),
(2, 'exception'),
(3, 'line'),
(4, 'line'),
(4, 'return')]
def _settrace_and_return(tracefunc):
sys.settrace(tracefunc)
sys._getframe().f_back.f_trace = tracefunc
def settrace_and_return(tracefunc):
_settrace_and_return(tracefunc)
settrace_and_return.events = [(1, 'return')]
def _settrace_and_raise(tracefunc):
sys.settrace(tracefunc)
sys._getframe().f_back.f_trace = tracefunc
raise RuntimeError
def settrace_and_raise(tracefunc):
try:
_settrace_and_raise(tracefunc)
except RuntimeError, exc:
pass
settrace_and_raise.events = [(2, 'exception'),
(3, 'line'),
(4, 'line'),
(4, 'return')]
# implicit return example
# This test is interesting because of the else: pass
# part of the code. The code generate for the true
# part of the if contains a jump past the else branch.
# The compiler then generates an implicit "return None"
# Internally, the compiler visits the pass statement
# and stores its line number for use on the next instruction.
# The next instruction is the implicit return None.
def ireturn_example():
a = 5
b = 5
if a == b:
b = a+1
else:
pass
ireturn_example.events = [(0, 'call'),
(1, 'line'),
(2, 'line'),
(3, 'line'),
(4, 'line'),
(6, 'line'),
(6, 'return')]
# Tight loop with while(1) example (SF #765624)
def tightloop_example():
items = range(0, 3)
try:
i = 0
while 1:
b = items[i]; i+=1
except IndexError:
pass
tightloop_example.events = [(0, 'call'),
(1, 'line'),
(2, 'line'),
(3, 'line'),
(4, 'line'),
(5, 'line'),
(5, 'line'),
(5, 'line'),
(5, 'line'),
(5, 'exception'),
(6, 'line'),
(7, 'line'),
(7, 'return')]
def tighterloop_example():
items = range(1, 4)
try:
i = 0
while 1: i = items[i]
except IndexError:
pass
tighterloop_example.events = [(0, 'call'),
(1, 'line'),
(2, 'line'),
(3, 'line'),
(4, 'line'),
(4, 'line'),
(4, 'line'),
(4, 'line'),
(4, 'exception'),
(5, 'line'),
(6, 'line'),
(6, 'return')]
def generator_function():
try:
yield True
"continued"
finally:
"finally"
def generator_example():
# any() will leave the generator before its end
x = any(generator_function())
# the following lines were not traced
for x in range(10):
y = x
generator_example.events = ([(0, 'call'),
(2, 'line'),
(-6, 'call'),
(-5, 'line'),
(-4, 'line'),
(-4, 'return'),
(-4, 'call'),
(-4, 'exception'),
(-1, 'line'),
(-1, 'return')] +
[(5, 'line'), (6, 'line')] * 10 +
[(5, 'line'), (5, 'return')])
class Tracer:
def __init__(self):
self.events = []
def trace(self, frame, event, arg):
self.events.append((frame.f_lineno, event))
return self.trace
def traceWithGenexp(self, frame, event, arg):
(o for o in [1])
self.events.append((frame.f_lineno, event))
return self.trace
class TraceTestCase(unittest.TestCase):
def compare_events(self, line_offset, events, expected_events):
events = [(l - line_offset, e) for (l, e) in events]
if events != expected_events:
self.fail(
"events did not match expectation:\n" +
"\n".join(difflib.ndiff([str(x) for x in expected_events],
[str(x) for x in events])))
def run_and_compare(self, func, events):
tracer = Tracer()
sys.settrace(tracer.trace)
func()
sys.settrace(None)
self.compare_events(func.func_code.co_firstlineno,
tracer.events, events)
def run_test(self, func):
self.run_and_compare(func, func.events)
def run_test2(self, func):
tracer = Tracer()
func(tracer.trace)
sys.settrace(None)
self.compare_events(func.func_code.co_firstlineno,
tracer.events, func.events)
def test_01_basic(self):
self.run_test(basic)
def test_02_arigo(self):
self.run_test(arigo_example)
def test_03_one_instr(self):
self.run_test(one_instr_line)
def test_04_no_pop_blocks(self):
self.run_test(no_pop_blocks)
def test_05_no_pop_tops(self):
self.run_test(no_pop_tops)
def test_06_call(self):
self.run_test(call)
def test_07_raise(self):
self.run_test(test_raise)
def test_08_settrace_and_return(self):
self.run_test2(settrace_and_return)
def test_09_settrace_and_raise(self):
self.run_test2(settrace_and_raise)
def test_10_ireturn(self):
self.run_test(ireturn_example)
def test_11_tightloop(self):
self.run_test(tightloop_example)
def test_12_tighterloop(self):
self.run_test(tighterloop_example)
def test_13_genexp(self):
self.run_test(generator_example)
# issue1265: if the trace function contains a generator,
# and if the traced function contains another generator
# that is not completely exhausted, the trace stopped.
# Worse: the 'finally' clause was not invoked.
tracer = Tracer()
sys.settrace(tracer.traceWithGenexp)
generator_example()
sys.settrace(None)
self.compare_events(generator_example.func_code.co_firstlineno,
tracer.events, generator_example.events)
def test_14_onliner_if(self):
def onliners():
if True: False
else: True
return 0
self.run_and_compare(
onliners,
[(0, 'call'),
(1, 'line'),
(3, 'line'),
(3, 'return')])
def test_15_loops(self):
# issue1750076: "while" expression is skipped by debugger
def for_example():
for x in range(2):
pass
self.run_and_compare(
for_example,
[(0, 'call'),
(1, 'line'),
(2, 'line'),
(1, 'line'),
(2, 'line'),
(1, 'line'),
(1, 'return')])
def while_example():
# While expression should be traced on every loop
x = 2
while x > 0:
x -= 1
self.run_and_compare(
while_example,
[(0, 'call'),
(2, 'line'),
(3, 'line'),
(4, 'line'),
(3, 'line'),
(4, 'line'),
(3, 'line'),
(3, 'return')])
def test_16_blank_lines(self):
exec("def f():\n" + "\n" * 256 + " pass")
self.run_and_compare(
f,
[(0, 'call'),
(257, 'line'),
(257, 'return')])
class RaisingTraceFuncTestCase(unittest.TestCase):
def trace(self, frame, event, arg):
"""A trace function that raises an exception in response to a
specific trace event."""
if event == self.raiseOnEvent:
raise ValueError # just something that isn't RuntimeError
else:
return self.trace
def f(self):
"""The function to trace; raises an exception if that's the case
we're testing, so that the 'exception' trace event fires."""
if self.raiseOnEvent == 'exception':
x = 0
y = 1/x
else:
return 1
def run_test_for_event(self, event):
"""Tests that an exception raised in response to the given event is
handled OK."""
self.raiseOnEvent = event
try:
for i in xrange(sys.getrecursionlimit() + 1):
sys.settrace(self.trace)
try:
self.f()
except ValueError:
pass
else:
self.fail("exception not thrown!")
except RuntimeError:
self.fail("recursion counter not reset")
# Test the handling of exceptions raised by each kind of trace event.
def test_call(self):
self.run_test_for_event('call')
def test_line(self):
self.run_test_for_event('line')
def test_return(self):
self.run_test_for_event('return')
def test_exception(self):
self.run_test_for_event('exception')
def test_trash_stack(self):
def f():
for i in range(5):
print i # line tracing will raise an exception at this line
def g(frame, why, extra):
if (why == 'line' and
frame.f_lineno == f.func_code.co_firstlineno + 2):
raise RuntimeError, "i am crashing"
return g
sys.settrace(g)
try:
f()
except RuntimeError:
# the test is really that this doesn't segfault:
import gc
gc.collect()
else:
self.fail("exception not propagated")
# 'Jump' tests: assigning to frame.f_lineno within a trace function
# moves the execution position - it's how debuggers implement a Jump
# command (aka. "Set next statement").
class JumpTracer:
"""Defines a trace function that jumps from one place to another,
with the source and destination lines of the jump being defined by
the 'jump' property of the function under test."""
def __init__(self, function):
self.function = function
self.jumpFrom = function.jump[0]
self.jumpTo = function.jump[1]
self.done = False
def trace(self, frame, event, arg):
if not self.done and frame.f_code == self.function.func_code:
firstLine = frame.f_code.co_firstlineno
if frame.f_lineno == firstLine + self.jumpFrom:
# Cope with non-integer self.jumpTo (because of
# no_jump_to_non_integers below).
try:
frame.f_lineno = firstLine + self.jumpTo
except TypeError:
frame.f_lineno = self.jumpTo
self.done = True
return self.trace
# The first set of 'jump' tests are for things that are allowed:
def jump_simple_forwards(output):
output.append(1)
output.append(2)
output.append(3)
jump_simple_forwards.jump = (1, 3)
jump_simple_forwards.output = [3]
def jump_simple_backwards(output):
output.append(1)
output.append(2)
jump_simple_backwards.jump = (2, 1)
jump_simple_backwards.output = [1, 1, 2]
def jump_out_of_block_forwards(output):
for i in 1, 2:
output.append(2)
for j in [3]: # Also tests jumping over a block
output.append(4)
output.append(5)
jump_out_of_block_forwards.jump = (3, 5)
jump_out_of_block_forwards.output = [2, 5]
def jump_out_of_block_backwards(output):
output.append(1)
for i in [1]:
output.append(3)
for j in [2]: # Also tests jumping over a block
output.append(5)
output.append(6)
output.append(7)
jump_out_of_block_backwards.jump = (6, 1)
jump_out_of_block_backwards.output = [1, 3, 5, 1, 3, 5, 6, 7]
def jump_to_codeless_line(output):
output.append(1)
# Jumping to this line should skip to the next one.
output.append(3)
jump_to_codeless_line.jump = (1, 2)
jump_to_codeless_line.output = [3]
def jump_to_same_line(output):
output.append(1)
output.append(2)
output.append(3)
jump_to_same_line.jump = (2, 2)
jump_to_same_line.output = [1, 2, 3]
# Tests jumping within a finally block, and over one.
def jump_in_nested_finally(output):
try:
output.append(2)
finally:
output.append(4)
try:
output.append(6)
finally:
output.append(8)
output.append(9)
jump_in_nested_finally.jump = (4, 9)
jump_in_nested_finally.output = [2, 9]
# The second set of 'jump' tests are for things that are not allowed:
def no_jump_too_far_forwards(output):
try:
output.append(2)
output.append(3)
except ValueError, e:
output.append('after' in str(e))
no_jump_too_far_forwards.jump = (3, 6)
no_jump_too_far_forwards.output = [2, True]
def no_jump_too_far_backwards(output):
try:
output.append(2)
output.append(3)
except ValueError, e:
output.append('before' in str(e))
no_jump_too_far_backwards.jump = (3, -1)
no_jump_too_far_backwards.output = [2, True]
# Test each kind of 'except' line.
def no_jump_to_except_1(output):
try:
output.append(2)
except:
e = sys.exc_info()[1]
output.append('except' in str(e))
no_jump_to_except_1.jump = (2, 3)
no_jump_to_except_1.output = [True]
def no_jump_to_except_2(output):
try:
output.append(2)
except ValueError:
e = sys.exc_info()[1]
output.append('except' in str(e))
no_jump_to_except_2.jump = (2, 3)
no_jump_to_except_2.output = [True]
def no_jump_to_except_3(output):
try:
output.append(2)
except ValueError, e:
output.append('except' in str(e))
no_jump_to_except_3.jump = (2, 3)
no_jump_to_except_3.output = [True]
def no_jump_to_except_4(output):
try:
output.append(2)
except (ValueError, RuntimeError), e:
output.append('except' in str(e))
no_jump_to_except_4.jump = (2, 3)
no_jump_to_except_4.output = [True]
def no_jump_forwards_into_block(output):
try:
output.append(2)
for i in 1, 2:
output.append(4)
except ValueError, e:
output.append('into' in str(e))
no_jump_forwards_into_block.jump = (2, 4)
no_jump_forwards_into_block.output = [True]
def no_jump_backwards_into_block(output):
try:
for i in 1, 2:
output.append(3)
output.append(4)
except ValueError, e:
output.append('into' in str(e))
no_jump_backwards_into_block.jump = (4, 3)
no_jump_backwards_into_block.output = [3, 3, True]
def no_jump_into_finally_block(output):
try:
try:
output.append(3)
x = 1
finally:
output.append(6)
except ValueError, e:
output.append('finally' in str(e))
no_jump_into_finally_block.jump = (4, 6)
no_jump_into_finally_block.output = [3, 6, True] # The 'finally' still runs
def no_jump_out_of_finally_block(output):
try:
try:
output.append(3)
finally:
output.append(5)
output.append(6)
except ValueError, e:
output.append('finally' in str(e))
no_jump_out_of_finally_block.jump = (5, 1)
no_jump_out_of_finally_block.output = [3, True]
# This verifies the line-numbers-must-be-integers rule.
def no_jump_to_non_integers(output):
try:
output.append(2)
except ValueError, e:
output.append('integer' in str(e))
no_jump_to_non_integers.jump = (2, "Spam")
no_jump_to_non_integers.output = [True]
# This verifies that you can't set f_lineno via _getframe or similar
# trickery.
def no_jump_without_trace_function():
try:
previous_frame = sys._getframe().f_back
previous_frame.f_lineno = previous_frame.f_lineno
except ValueError, e:
# This is the exception we wanted; make sure the error message
# talks about trace functions.
if 'trace' not in str(e):
raise
else:
# Something's wrong - the expected exception wasn't raised.
raise RuntimeError, "Trace-function-less jump failed to fail"
class JumpTestCase(unittest.TestCase):
def compare_jump_output(self, expected, received):
if received != expected:
self.fail( "Outputs don't match:\n" +
"Expected: " + repr(expected) + "\n" +
"Received: " + repr(received))
def run_test(self, func):
tracer = JumpTracer(func)
sys.settrace(tracer.trace)
output = []
func(output)
sys.settrace(None)
self.compare_jump_output(func.output, output)
def test_01_jump_simple_forwards(self):
self.run_test(jump_simple_forwards)
def test_02_jump_simple_backwards(self):
self.run_test(jump_simple_backwards)
def test_03_jump_out_of_block_forwards(self):
self.run_test(jump_out_of_block_forwards)
def test_04_jump_out_of_block_backwards(self):
self.run_test(jump_out_of_block_backwards)
def test_05_jump_to_codeless_line(self):
self.run_test(jump_to_codeless_line)
def test_06_jump_to_same_line(self):
self.run_test(jump_to_same_line)
def test_07_jump_in_nested_finally(self):
self.run_test(jump_in_nested_finally)
def test_08_no_jump_too_far_forwards(self):
self.run_test(no_jump_too_far_forwards)
def test_09_no_jump_too_far_backwards(self):
self.run_test(no_jump_too_far_backwards)
def test_10_no_jump_to_except_1(self):
self.run_test(no_jump_to_except_1)
def test_11_no_jump_to_except_2(self):
self.run_test(no_jump_to_except_2)
def test_12_no_jump_to_except_3(self):
self.run_test(no_jump_to_except_3)
def test_13_no_jump_to_except_4(self):
self.run_test(no_jump_to_except_4)
def test_14_no_jump_forwards_into_block(self):
self.run_test(no_jump_forwards_into_block)
def test_15_no_jump_backwards_into_block(self):
self.run_test(no_jump_backwards_into_block)
def test_16_no_jump_into_finally_block(self):
self.run_test(no_jump_into_finally_block)
def test_17_no_jump_out_of_finally_block(self):
self.run_test(no_jump_out_of_finally_block)
def test_18_no_jump_to_non_integers(self):
self.run_test(no_jump_to_non_integers)
def test_19_no_jump_without_trace_function(self):
no_jump_without_trace_function()
def test_main():
tests = [TraceTestCase,
RaisingTraceFuncTestCase]
if not test_support.is_jython:
tests.append(JumpTestCase)
else:
del TraceTestCase.test_02_arigo
del TraceTestCase.test_05_no_pop_tops
del TraceTestCase.test_07_raise
del TraceTestCase.test_09_settrace_and_raise
del TraceTestCase.test_10_ireturn
del TraceTestCase.test_11_tightloop
del TraceTestCase.test_12_tighterloop
del TraceTestCase.test_13_genexp
del TraceTestCase.test_14_onliner_if
del TraceTestCase.test_15_loops
test_support.run_unittest(*tests)
if __name__ == "__main__":
test_main()