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colorize interactive shell examples

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Mark Pilgrim
2009-06-08 22:43:48 -04:00
parent cd6260adf1
commit be2b7d3546
16 changed files with 1003 additions and 1020 deletions
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unit-testing.html
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@@ -202,8 +202,8 @@ while n >= integer:
print('subtracting {0} from input, adding {1} to output'.format(integer, numeral))</code></pre>
<p>With the debug <code>print()</code> statements, the output looks like this:
<pre class=screen>
<samp class=p>>>> </samp><kbd>import roman1</kbd>
<samp class=p>>>> </samp><kbd>roman1.to_roman(1424)</kbd>
<samp class=p>>>> </samp><kbd class=pp>import roman1</kbd>
<samp class=p>>>> </samp><kbd class=pp>roman1.to_roman(1424)</kbd>
<samp>subtracting 1000 from input, adding M to output
subtracting 400 from input, adding CD to output
subtracting 10 from input, adding X to output
@@ -229,13 +229,13 @@ OK</samp></pre>
<aside>The Pythonic way to halt and catch fire is to raise an exception.</aside>
<p>It is not enough to test that functions succeed when given good input; you must also test that they fail when given bad input. And not just any sort of failure; they must fail in the way you expect.
<pre class=screen>
<samp class=p>>>> </samp><kbd>import roman1</kbd>
<samp class=p>>>> </samp><kbd>roman1.to_roman(4000)</kbd>
<samp>'MMMM'</samp>
<samp class=p>>>> </samp><kbd>roman1.to_roman(5000)</kbd>
<samp>'MMMMM'</samp>
<a><samp class=p>>>> </samp><kbd>roman1.to_roman(9000)</kbd> <span class=u>&#x2460;</span></a>
<samp>'MMMMMMMMM'</samp></pre>
<samp class=p>>>> </samp><kbd class=pp>import roman1</kbd>
<samp class=p>>>> </samp><kbd class=pp>roman1.to_roman(4000)</kbd>
<samp class=pp>'MMMM'</samp>
<samp class=p>>>> </samp><kbd class=pp>roman1.to_roman(5000)</kbd>
<samp class=pp>'MMMMM'</samp>
<a><samp class=p>>>> </samp><kbd class=pp>roman1.to_roman(9000)</kbd> <span class=u>&#x2460;</span></a>
<samp class=pp>'MMMMMMMMM'</samp></pre>
<ol>
<li>That&#8217;s definitely not what you wanted &mdash; that&#8217;s not even a valid Roman numeral! In fact, each of these numbers is outside the range of acceptable input, but the function returns a bogus value anyway. Silently returning bad values is <em>baaaaaaad</em>; if a program is going to fail, it is far better that it fail quickly and noisily. &#8220;Halt and catch fire,&#8221; as the saying goes. The Pythonic way to halt and catch fire is to raise an exception.
</ol>
@@ -344,11 +344,11 @@ OK</samp></pre>
<p>Along with testing numbers that are too large, you need to test numbers that are too small. As <a href=#divingin>we noted in our functional requirements</a>, Roman numerals cannot express <code>0</code> or negative numbers.
<pre class=screen>
<samp class=p>>>> </samp><kbd>import roman2</kbd>
<samp class=p>>>> </samp><kbd>roman2.to_roman(0)</kbd>
<samp>''</samp>
<samp class=p>>>> </samp><kbd>roman2.to_roman(-1)</kbd>
<samp>''</samp></pre>
<samp class=p>>>> </samp><kbd class=pp>import roman2</kbd>
<samp class=p>>>> </samp><kbd class=pp>roman2.to_roman(0)</kbd>
<samp class=pp>''</samp>
<samp class=p>>>> </samp><kbd class=pp>roman2.to_roman(-1)</kbd>
<samp class=pp>''</samp></pre>
<p>Well <em>that&#8217;s</em> not good. Let&#8217;s add tests for each of these conditions.
@@ -441,11 +441,11 @@ OK</samp></pre>
<p>There was one more <a href=#divingin>functional requirement</a> for converting numbers to Roman numerals: dealing with non-integers.
<pre class=screen>
<samp class=p>>>> </samp><kbd>import roman3</kbd>
<a><samp class=p>>>> </samp><kbd>roman3.to_roman(0.5)</kbd> <span class=u>&#x2460;</span></a>
<samp>''</samp>
<a><samp class=p>>>> </samp><kbd>roman3.to_roman(1.5)</kbd> <span class=u>&#x2461;</span></a>
<samp>'I'</samp></pre>
<samp class=p>>>> </samp><kbd class=pp>import roman3</kbd>
<a><samp class=p>>>> </samp><kbd class=pp>roman3.to_roman(0.5)</kbd> <span class=u>&#x2460;</span></a>
<samp class=pp>''</samp>
<a><samp class=p>>>> </samp><kbd class=pp>roman3.to_roman(1.5)</kbd> <span class=u>&#x2461;</span></a>
<samp class=pp>'I'</samp></pre>
<ol>
<li>Oh, that&#8217;s bad.
<li>Oh, that&#8217;s even worse. Both of these cases should raise an exception. Instead, they give bogus results.