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POC++ test to verify equality operator is kept consistent with struct over time
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  1. POC++ test to verify equality operator is kept consistent with struct over time
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    copied!<p>I voted up @TomalakGeretkal for a good note about by-contract; I'm haven't accepted an answer as my question is how to programatically check the equals function. </p> <hr> <p>I have a POD struct &amp; an equality operator, a (very) small part of a system with >100 engineers. </p> <p>Over time I expect the struct to be modified (members added/removed/reordered) and I want to write a test to verify that the equality op is testing every member of the struct (eg is kept up to date as the struct changes).</p> <p>As Tomalak pointed out - comments &amp; "by contract" is often the best/only way to enforce this; however in my situation I expect issues and want to explore whether there are any ways to proactively catch (at least many) of the modifications.</p> <p>I'm not coming up with a satisfactory answer - this is the best I've thought of:</p> <pre><code>-new up two instances struct (x, y), fill each with identical non-zero data. -check x==y -modify x "byte by byte" -take ptr to be (unsigned char*)&amp;x -iterator over ptr (for sizeof(x)) -increment the current byte -check !(x==y) -decrement the current byte -check x==y </code></pre> <p>The test passes if the equality operator caught every byte (NOTE: there is a caveat to this - not all bytes are used in the compilers representation of x, therefore the test would have to 'skip' these bytes - eg hard code ignore bytes)</p> <p>My proposed test has significant problems: (at least) the 'don't care' bytes, and the fact that incrementing one byte of the types in x may not result in a valid value for the variable at that memory location.</p> <p>Any better solutions?</p> <p>(This shouldn't matter, but I'm using VS2008, rtti is off, googletest suite)</p>
 

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