| 1 | <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> |
| 2 | <html> |
| 3 | <head> |
| 4 | <link rel="STYLESHEET" href="lib.css" type='text/css' /> |
| 5 | <link rel="SHORTCUT ICON" href="../icons/pyfav.png" type="image/png" /> |
| 6 | <link rel='start' href='../index.html' title='Python Documentation Index' /> |
| 7 | <link rel="first" href="lib.html" title='Python Library Reference' /> |
| 8 | <link rel='contents' href='contents.html' title="Contents" /> |
| 9 | <link rel='index' href='genindex.html' title='Index' /> |
| 10 | <link rel='last' href='about.html' title='About this document...' /> |
| 11 | <link rel='help' href='about.html' title='About this document...' /> |
| 12 | <link rel="next" href="doctest-soapbox.html" /> |
| 13 | <link rel="prev" href="doctest-advanced-api.html" /> |
| 14 | <link rel="parent" href="module-doctest.html" /> |
| 15 | <link rel="next" href="doctest-soapbox.html" /> |
| 16 | <meta name='aesop' content='information' /> |
| 17 | <title>5.2.7 Debugging</title> |
| 18 | </head> |
| 19 | <body> |
| 20 | <DIV CLASS="navigation"> |
| 21 | <div id='top-navigation-panel' xml:id='top-navigation-panel'> |
| 22 | <table align="center" width="100%" cellpadding="0" cellspacing="2"> |
| 23 | <tr> |
| 24 | <td class='online-navigation'><a rel="prev" title="5.2.6.6 OutputChecker objects" |
| 25 | href="doctest-OutputChecker.html"><img src='../icons/previous.png' |
| 26 | border='0' height='32' alt='Previous Page' width='32' /></A></td> |
| 27 | <td class='online-navigation'><a rel="parent" title="5.2 doctest " |
| 28 | href="module-doctest.html"><img src='../icons/up.png' |
| 29 | border='0' height='32' alt='Up One Level' width='32' /></A></td> |
| 30 | <td class='online-navigation'><a rel="next" title="5.2.8 Soapbox" |
| 31 | href="doctest-soapbox.html"><img src='../icons/next.png' |
| 32 | border='0' height='32' alt='Next Page' width='32' /></A></td> |
| 33 | <td align="center" width="100%">Python Library Reference</td> |
| 34 | <td class='online-navigation'><a rel="contents" title="Table of Contents" |
| 35 | href="contents.html"><img src='../icons/contents.png' |
| 36 | border='0' height='32' alt='Contents' width='32' /></A></td> |
| 37 | <td class='online-navigation'><a href="modindex.html" title="Module Index"><img src='../icons/modules.png' |
| 38 | border='0' height='32' alt='Module Index' width='32' /></a></td> |
| 39 | <td class='online-navigation'><a rel="index" title="Index" |
| 40 | href="genindex.html"><img src='../icons/index.png' |
| 41 | border='0' height='32' alt='Index' width='32' /></A></td> |
| 42 | </tr></table> |
| 43 | <div class='online-navigation'> |
| 44 | <b class="navlabel">Previous:</b> |
| 45 | <a class="sectref" rel="prev" href="doctest-OutputChecker.html">5.2.6.6 OutputChecker objects</A> |
| 46 | <b class="navlabel">Up:</b> |
| 47 | <a class="sectref" rel="parent" href="module-doctest.html">5.2 doctest </A> |
| 48 | <b class="navlabel">Next:</b> |
| 49 | <a class="sectref" rel="next" href="doctest-soapbox.html">5.2.8 Soapbox</A> |
| 50 | </div> |
| 51 | <hr /></div> |
| 52 | </DIV> |
| 53 | <!--End of Navigation Panel--> |
| 54 | |
| 55 | <H2><A NAME="SECTION007270000000000000000"></A><A NAME="doctest-debugging"></A> |
| 56 | <BR> |
| 57 | 5.2.7 Debugging |
| 58 | </H2> |
| 59 | |
| 60 | <P> |
| 61 | Doctest provides several mechanisms for debugging doctest examples: |
| 62 | |
| 63 | <P> |
| 64 | |
| 65 | <UL> |
| 66 | <LI>Several functions convert doctests to executable Python |
| 67 | programs, which can be run under the Python debugger, <tt class="module"><a href="module-pdb.html">pdb</a></tt>. |
| 68 | </LI> |
| 69 | <LI>The <tt class="class">DebugRunner</tt> class is a subclass of |
| 70 | <tt class="class">DocTestRunner</tt> that raises an exception for the first |
| 71 | failing example, containing information about that example. |
| 72 | This information can be used to perform post-mortem debugging on |
| 73 | the example. |
| 74 | </LI> |
| 75 | <LI>The <tt class="module"><a href="module-unittest.html">unittest</a></tt> cases generated by <tt class="function">DocTestSuite()</tt> |
| 76 | support the <tt class="method">debug()</tt> method defined by |
| 77 | <tt class="class"><tt class="module"><a href="module-unittest.html">unittest</a></tt>.TestCase</tt>. |
| 78 | </LI> |
| 79 | <LI>You can add a call to <tt class="function"><tt class="module"><a href="module-pdb.html">pdb</a></tt>.set_trace()</tt> in a |
| 80 | doctest example, and you'll drop into the Python debugger when that |
| 81 | line is executed. Then you can inspect current values of variables, |
| 82 | and so on. For example, suppose <span class="file">a.py</span> contains just this |
| 83 | module docstring: |
| 84 | |
| 85 | <P> |
| 86 | <div class="verbatim"><pre> |
| 87 | """ |
| 88 | >>> def f(x): |
| 89 | ... g(x*2) |
| 90 | >>> def g(x): |
| 91 | ... print x+3 |
| 92 | ... import pdb; pdb.set_trace() |
| 93 | >>> f(3) |
| 94 | 9 |
| 95 | """ |
| 96 | </pre></div> |
| 97 | |
| 98 | <P> |
| 99 | Then an interactive Python session may look like this: |
| 100 | |
| 101 | <P> |
| 102 | <div class="verbatim"><pre> |
| 103 | >>> import a, doctest |
| 104 | >>> doctest.testmod(a) |
| 105 | --Return-- |
| 106 | > <doctest a[1]>(3)g()->None |
| 107 | -> import pdb; pdb.set_trace() |
| 108 | (Pdb) list |
| 109 | 1 def g(x): |
| 110 | 2 print x+3 |
| 111 | 3 -> import pdb; pdb.set_trace() |
| 112 | [EOF] |
| 113 | (Pdb) print x |
| 114 | 6 |
| 115 | (Pdb) step |
| 116 | --Return-- |
| 117 | > <doctest a[0]>(2)f()->None |
| 118 | -> g(x*2) |
| 119 | (Pdb) list |
| 120 | 1 def f(x): |
| 121 | 2 -> g(x*2) |
| 122 | [EOF] |
| 123 | (Pdb) print x |
| 124 | 3 |
| 125 | (Pdb) step |
| 126 | --Return-- |
| 127 | > <doctest a[2]>(1)?()->None |
| 128 | -> f(3) |
| 129 | (Pdb) cont |
| 130 | (0, 3) |
| 131 | >>> |
| 132 | </pre></div> |
| 133 | |
| 134 | <P> |
| 135 | |
| 136 | <span class="versionnote">Changed in version 2.4: |
| 137 | The ability to use <code><tt class="module"><a href="module-pdb.html">pdb</a></tt>.set_trace()</code> |
| 138 | usefully inside doctests was added.</span> |
| 139 | |
| 140 | </LI> |
| 141 | </UL> |
| 142 | |
| 143 | <P> |
| 144 | Functions that convert doctests to Python code, and possibly run |
| 145 | the synthesized code under the debugger: |
| 146 | |
| 147 | <P> |
| 148 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 149 | <td><nobr><b><tt id='l2h-1110' xml:id='l2h-1110' class="function">script_from_examples</tt></b>(</nobr></td> |
| 150 | <td><var>s</var>)</td></tr></table></dt> |
| 151 | <dd> |
| 152 | Convert text with examples to a script. |
| 153 | |
| 154 | <P> |
| 155 | Argument <var>s</var> is a string containing doctest examples. The string |
| 156 | is converted to a Python script, where doctest examples in <var>s</var> |
| 157 | are converted to regular code, and everything else is converted to |
| 158 | Python comments. The generated script is returned as a string. |
| 159 | For example, |
| 160 | |
| 161 | <P> |
| 162 | <div class="verbatim"><pre> |
| 163 | import doctest |
| 164 | print doctest.script_from_examples(r""" |
| 165 | Set x and y to 1 and 2. |
| 166 | >>> x, y = 1, 2 |
| 167 | |
| 168 | Print their sum: |
| 169 | >>> print x+y |
| 170 | 3 |
| 171 | """) |
| 172 | </pre></div> |
| 173 | |
| 174 | <P> |
| 175 | displays: |
| 176 | |
| 177 | <P> |
| 178 | <div class="verbatim"><pre> |
| 179 | # Set x and y to 1 and 2. |
| 180 | x, y = 1, 2 |
| 181 | # |
| 182 | # Print their sum: |
| 183 | print x+y |
| 184 | # Expected: |
| 185 | ## 3 |
| 186 | </pre></div> |
| 187 | |
| 188 | <P> |
| 189 | This function is used internally by other functions (see below), but |
| 190 | can also be useful when you want to transform an interactive Python |
| 191 | session into a Python script. |
| 192 | |
| 193 | <P> |
| 194 | |
| 195 | <span class="versionnote">New in version 2.4.</span> |
| 196 | |
| 197 | </dl> |
| 198 | |
| 199 | <P> |
| 200 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 201 | <td><nobr><b><tt id='l2h-1111' xml:id='l2h-1111' class="function">testsource</tt></b>(</nobr></td> |
| 202 | <td><var>module, name</var>)</td></tr></table></dt> |
| 203 | <dd> |
| 204 | Convert the doctest for an object to a script. |
| 205 | |
| 206 | <P> |
| 207 | Argument <var>module</var> is a module object, or dotted name of a module, |
| 208 | containing the object whose doctests are of interest. Argument |
| 209 | <var>name</var> is the name (within the module) of the object with the |
| 210 | doctests of interest. The result is a string, containing the |
| 211 | object's docstring converted to a Python script, as described for |
| 212 | <tt class="function">script_from_examples()</tt> above. For example, if module |
| 213 | <span class="file">a.py</span> contains a top-level function <tt class="function">f()</tt>, then |
| 214 | |
| 215 | <P> |
| 216 | <div class="verbatim"><pre> |
| 217 | import a, doctest |
| 218 | print doctest.testsource(a, "a.f") |
| 219 | </pre></div> |
| 220 | |
| 221 | <P> |
| 222 | prints a script version of function <tt class="function">f()</tt>'s docstring, |
| 223 | with doctests converted to code, and the rest placed in comments. |
| 224 | |
| 225 | <P> |
| 226 | |
| 227 | <span class="versionnote">New in version 2.3.</span> |
| 228 | |
| 229 | </dl> |
| 230 | |
| 231 | <P> |
| 232 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 233 | <td><nobr><b><tt id='l2h-1112' xml:id='l2h-1112' class="function">debug</tt></b>(</nobr></td> |
| 234 | <td><var>module, name</var><big>[</big><var>, pm</var><big>]</big><var></var>)</td></tr></table></dt> |
| 235 | <dd> |
| 236 | Debug the doctests for an object. |
| 237 | |
| 238 | <P> |
| 239 | The <var>module</var> and <var>name</var> arguments are the same as for function |
| 240 | <tt class="function">testsource()</tt> above. The synthesized Python script for the |
| 241 | named object's docstring is written to a temporary file, and then that |
| 242 | file is run under the control of the Python debugger, <tt class="module"><a href="module-pdb.html">pdb</a></tt>. |
| 243 | |
| 244 | <P> |
| 245 | A shallow copy of <code><var>module</var>.__dict__</code> is used for both local |
| 246 | and global execution context. |
| 247 | |
| 248 | <P> |
| 249 | Optional argument <var>pm</var> controls whether post-mortem debugging is |
| 250 | used. If <var>pm</var> has a true value, the script file is run directly, and |
| 251 | the debugger gets involved only if the script terminates via raising an |
| 252 | unhandled exception. If it does, then post-mortem debugging is invoked, |
| 253 | via <code><tt class="module"><a href="module-pdb.html">pdb</a></tt>.post_mortem()</code>, passing the traceback object |
| 254 | from the unhandled exception. If <var>pm</var> is not specified, or is false, |
| 255 | the script is run under the debugger from the start, via passing an |
| 256 | appropriate <tt class="function">execfile()</tt> call to <code><tt class="module"><a href="module-pdb.html">pdb</a></tt>.run()</code>. |
| 257 | |
| 258 | <P> |
| 259 | |
| 260 | <span class="versionnote">New in version 2.3.</span> |
| 261 | |
| 262 | <P> |
| 263 | |
| 264 | <span class="versionnote">Changed in version 2.4: |
| 265 | The <var>pm</var> argument was added.</span> |
| 266 | |
| 267 | </dl> |
| 268 | |
| 269 | <P> |
| 270 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 271 | <td><nobr><b><tt id='l2h-1113' xml:id='l2h-1113' class="function">debug_src</tt></b>(</nobr></td> |
| 272 | <td><var>src</var><big>[</big><var>, pm</var><big>]</big><var></var><big>[</big><var>, globs</var><big>]</big><var></var>)</td></tr></table></dt> |
| 273 | <dd> |
| 274 | Debug the doctests in a string. |
| 275 | |
| 276 | <P> |
| 277 | This is like function <tt class="function">debug()</tt> above, except that |
| 278 | a string containing doctest examples is specified directly, via |
| 279 | the <var>src</var> argument. |
| 280 | |
| 281 | <P> |
| 282 | Optional argument <var>pm</var> has the same meaning as in function |
| 283 | <tt class="function">debug()</tt> above. |
| 284 | |
| 285 | <P> |
| 286 | Optional argument <var>globs</var> gives a dictionary to use as both |
| 287 | local and global execution context. If not specified, or <code>None</code>, |
| 288 | an empty dictionary is used. If specified, a shallow copy of the |
| 289 | dictionary is used. |
| 290 | |
| 291 | <P> |
| 292 | |
| 293 | <span class="versionnote">New in version 2.4.</span> |
| 294 | |
| 295 | </dl> |
| 296 | |
| 297 | <P> |
| 298 | The <tt class="class">DebugRunner</tt> class, and the special exceptions it may raise, |
| 299 | are of most interest to testing framework authors, and will only be |
| 300 | sketched here. See the source code, and especially <tt class="class">DebugRunner</tt>'s |
| 301 | docstring (which is a doctest!) for more details: |
| 302 | |
| 303 | <P> |
| 304 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 305 | <td><nobr><b><span class="typelabel">class</span> <tt id='l2h-1114' xml:id='l2h-1114' class="class">DebugRunner</tt></b>(</nobr></td> |
| 306 | <td><var></var><big>[</big><var>checker</var><big>]</big><var></var><big>[</big><var>, |
| 307 | verbose</var><big>]</big><var></var><big>[</big><var>, optionflags</var><big>]</big><var></var>)</td></tr></table></dt> |
| 308 | <dd> |
| 309 | |
| 310 | <P> |
| 311 | A subclass of <tt class="class">DocTestRunner</tt> that raises an exception as |
| 312 | soon as a failure is encountered. If an unexpected exception |
| 313 | occurs, an <tt class="exception">UnexpectedException</tt> exception is raised, |
| 314 | containing the test, the example, and the original exception. If |
| 315 | the output doesn't match, then a <tt class="exception">DocTestFailure</tt> |
| 316 | exception is raised, containing the test, the example, and the |
| 317 | actual output. |
| 318 | |
| 319 | <P> |
| 320 | For information about the constructor parameters and methods, see |
| 321 | the documentation for <tt class="class">DocTestRunner</tt> in |
| 322 | section <A href="doctest-advanced-api.html#doctest-advanced-api">5.2.6</A>. |
| 323 | </dl> |
| 324 | |
| 325 | <P> |
| 326 | There are two exceptions that may be raised by <tt class="class">DebugRunner</tt> |
| 327 | instances: |
| 328 | |
| 329 | <P> |
| 330 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 331 | <td><nobr><b><span class="typelabel">exception</span> <tt id='l2h-1115' xml:id='l2h-1115' class="exception">DocTestFailure</tt></b>(</nobr></td> |
| 332 | <td><var>test, example, got</var>)</td></tr></table></dt> |
| 333 | <dd> |
| 334 | An exception thrown by <tt class="class">DocTestRunner</tt> to signal that a |
| 335 | doctest example's actual output did not match its expected output. |
| 336 | The constructor arguments are used to initialize the member |
| 337 | variables of the same names. |
| 338 | </dl> |
| 339 | <tt class="exception">DocTestFailure</tt> defines the following member variables: |
| 340 | <dl><dt><b><tt id='l2h-1116' xml:id='l2h-1116' class="member">test</tt></b></dt> |
| 341 | <dd> |
| 342 | The <tt class="class">DocTest</tt> object that was being run when the example failed. |
| 343 | </dl> |
| 344 | <dl><dt><b><tt id='l2h-1117' xml:id='l2h-1117' class="member">example</tt></b></dt> |
| 345 | <dd> |
| 346 | The <tt class="class">Example</tt> that failed. |
| 347 | </dl> |
| 348 | <dl><dt><b><tt id='l2h-1118' xml:id='l2h-1118' class="member">got</tt></b></dt> |
| 349 | <dd> |
| 350 | The example's actual output. |
| 351 | </dl> |
| 352 | |
| 353 | <P> |
| 354 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 355 | <td><nobr><b><span class="typelabel">exception</span> <tt id='l2h-1119' xml:id='l2h-1119' class="exception">UnexpectedException</tt></b>(</nobr></td> |
| 356 | <td><var>test, example, exc_info</var>)</td></tr></table></dt> |
| 357 | <dd> |
| 358 | An exception thrown by <tt class="class">DocTestRunner</tt> to signal that a |
| 359 | doctest example raised an unexpected exception. The constructor |
| 360 | arguments are used to initialize the member variables of the same |
| 361 | names. |
| 362 | </dl> |
| 363 | <tt class="exception">UnexpectedException</tt> defines the following member variables: |
| 364 | <dl><dt><b><tt id='l2h-1120' xml:id='l2h-1120' class="member">test</tt></b></dt> |
| 365 | <dd> |
| 366 | The <tt class="class">DocTest</tt> object that was being run when the example failed. |
| 367 | </dl> |
| 368 | <dl><dt><b><tt id='l2h-1121' xml:id='l2h-1121' class="member">example</tt></b></dt> |
| 369 | <dd> |
| 370 | The <tt class="class">Example</tt> that failed. |
| 371 | </dl> |
| 372 | <dl><dt><b><tt id='l2h-1122' xml:id='l2h-1122' class="member">exc_info</tt></b></dt> |
| 373 | <dd> |
| 374 | A tuple containing information about the unexpected exception, as |
| 375 | returned by <tt class="function">sys.exc_info()</tt>. |
| 376 | </dl> |
| 377 | |
| 378 | <P> |
| 379 | |
| 380 | <DIV CLASS="navigation"> |
| 381 | <div class='online-navigation'> |
| 382 | <p></p><hr /> |
| 383 | <table align="center" width="100%" cellpadding="0" cellspacing="2"> |
| 384 | <tr> |
| 385 | <td class='online-navigation'><a rel="prev" title="5.2.6.6 OutputChecker objects" |
| 386 | href="doctest-OutputChecker.html"><img src='../icons/previous.png' |
| 387 | border='0' height='32' alt='Previous Page' width='32' /></A></td> |
| 388 | <td class='online-navigation'><a rel="parent" title="5.2 doctest " |
| 389 | href="module-doctest.html"><img src='../icons/up.png' |
| 390 | border='0' height='32' alt='Up One Level' width='32' /></A></td> |
| 391 | <td class='online-navigation'><a rel="next" title="5.2.8 Soapbox" |
| 392 | href="doctest-soapbox.html"><img src='../icons/next.png' |
| 393 | border='0' height='32' alt='Next Page' width='32' /></A></td> |
| 394 | <td align="center" width="100%">Python Library Reference</td> |
| 395 | <td class='online-navigation'><a rel="contents" title="Table of Contents" |
| 396 | href="contents.html"><img src='../icons/contents.png' |
| 397 | border='0' height='32' alt='Contents' width='32' /></A></td> |
| 398 | <td class='online-navigation'><a href="modindex.html" title="Module Index"><img src='../icons/modules.png' |
| 399 | border='0' height='32' alt='Module Index' width='32' /></a></td> |
| 400 | <td class='online-navigation'><a rel="index" title="Index" |
| 401 | href="genindex.html"><img src='../icons/index.png' |
| 402 | border='0' height='32' alt='Index' width='32' /></A></td> |
| 403 | </tr></table> |
| 404 | <div class='online-navigation'> |
| 405 | <b class="navlabel">Previous:</b> |
| 406 | <a class="sectref" rel="prev" href="doctest-OutputChecker.html">5.2.6.6 OutputChecker objects</A> |
| 407 | <b class="navlabel">Up:</b> |
| 408 | <a class="sectref" rel="parent" href="module-doctest.html">5.2 doctest </A> |
| 409 | <b class="navlabel">Next:</b> |
| 410 | <a class="sectref" rel="next" href="doctest-soapbox.html">5.2.8 Soapbox</A> |
| 411 | </div> |
| 412 | </div> |
| 413 | <hr /> |
| 414 | <span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span> |
| 415 | </DIV> |
| 416 | <!--End of Navigation Panel--> |
| 417 | <ADDRESS> |
| 418 | See <i><a href="about.html">About this document...</a></i> for information on suggesting changes. |
| 419 | </ADDRESS> |
| 420 | </BODY> |
| 421 | </HTML> |