Increasing coverage with try-except-finally and a context-manager

Question

This is the flow that I have in my program

277: try:
278:    with open(r"c:\afile.txt", "w") as aFile:
...:        pass # write data, other exceptions/errors can occur here that have to be handled by the caller
329: except IOError as ex:
...:    print ex
332: finally:
333:    if os.path.exists(r"c:\afile.txt"):
334:        shutil.copy(r"c:\afile.txt", r"c:\dest.txt")

I've got all paths covered except for from line 278 to line 333

• I got a normal happy-flow.
• I stubbed __builtin__.open to raise IOError when the open is called with said file name

But how do I go from 278 to 333. Is this even possible?

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Additional information: - using coverage.py 3.4 (we can't upgrade to 3.5)

Answer 1

One usually handles the flow in the following way

try:
    with open(r"C:\file.txt", "w") as aFile:
        a.File.write("!")
    if os.path.exists(r"C:\file.txt"):
        shutil.copy(r"C:\file.txt", r"C:\dest.txt")
except IOError as ex:
    print ex