micropython/tests/misc/print_exception.py

import sys
try:
    try:
        import uio as io
    except ImportError:
        import io
except ImportError:
    print("SKIP")
    raise SystemExit

if hasattr(sys, 'print_exception'):
    print_exception = sys.print_exception
else:
    import traceback
    print_exception = lambda e, f: traceback.print_exception(None, e, sys.exc_info()[2], file=f)

def print_exc(e):
    buf = io.StringIO()
    print_exception(e, buf)
    s = buf.getvalue()
    for l in s.split("\n"):
        # uPy on pyboard prints <stdin> as file, so remove filename.
        if l.startswith("  File "):
            l = l.split('"')
            print(l[0], l[2])
        # uPy and CPy tracebacks differ in that CPy prints a source line for
        # each traceback entry. In this case, we know that offending line
        # has 4-space indent, so filter it out.
        elif not l.startswith("    "):
            print(l)

# basic exception message
try:
    raise Exception('msg')
except Exception as e:
    print('caught')
    print_exc(e)

# exception message with more than 1 source-code line
def f():
    g()
def g():
    raise Exception('fail')
try:
    f()
except Exception as e:
    print('caught')
    print_exc(e)

# Here we have a function with lots of bytecode generated for a single source-line, and
# there is an error right at the end of the bytecode.  It should report the correct line.
def f():
    f([1, 2], [1, 2], [1, 2], {1:1, 1:1, 1:1, 1:1, 1:1, 1:1, 1:f.X})
    return 1
try:
    f()
except Exception as e:
    print_exc(e)

# Test non-stream object passed as output object, only valid for uPy
if hasattr(sys, 'print_exception'):
    try:
        sys.print_exception(Exception, 1)
        had_exception = False
    except OSError:
        had_exception = True
    assert had_exception