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  67 >Writing A Test Case</A
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  69 ><P
  70 >The easiest way to prepare a new test case is to base it
  71       on an existing one for a similar situation.  There are two major
  72       categories of tests: batch or interactive.  Batch oriented tests
  73       are usually easier to write.</P
  74 ><P
  75 >The GCC tests are a good example of batch oriented tests.
  76       All GCC tests consist primarily of a call to a single common
  77       procedure, Since all the tests either have no output, or only
  78       have a few warning messages when successfully compiled.  Any
  79       non-warning output is a test failure.  All the C code needed is
  80       kept in the test directory.  The test driver, written in Tcl,
  81       need only get a listing of all the C files in the directory, and
  82       compile them all using a generic procedure. This procedure and a
  83       few others supporting for these tests are kept in the library
  84       module <TT
  85 CLASS="FILENAME"
  86 >lib/c-torture.exp</TT
  87 > in the GCC test
  88       suite. Most tests of this kind use very few
  89       <SPAN
  90 CLASS="PRODUCTNAME"
  91 >expect</SPAN
  92 > features, and are coded almost
  93       purely in Tcl.</P
  94 ><P
  95 >Writing the complete suite of C tests, then, consisted of
  96       these steps:</P
  97 ><P
  98 ></P
  99 ><UL
 100 ><LI
 101 STYLE="list-style-type: disc"
 102 ><P
 103 >Copying all the C code into the test directory.
 104       These tests were based on the C-torture test created by Torbjorn
 105       Granlund (on behalf of the Free Software Foundation) for GCC
 106       development.</P
 107 ></LI
 108 ><LI
 109 STYLE="list-style-type: disc"
 110 ><P
 111 >Writing (and debugging) the generic Tcl procedures for
 112       compilation.</P
 113 ></LI
 114 ><LI
 115 STYLE="list-style-type: disc"
 116 ><P
 117 >Writing the simple test driver: its main task is to
 118       search the directory (using the Tcl procedure
 119       <I
 120 CLASS="EMPHASIS"
 121 >glob</I
 122 > for filename expansion with wildcards)
 123       and call a Tcl procedure with each filename.  It also checks for
 124       a few errors from the testing procedure.</P
 125 ></LI
 126 ></UL
 127 ><P
 128 >Testing interactive programs is intrinsically more
 129       complex.  Tests for most interactive programs require some trial
 130       and error before they are complete.</P
 131 ><P
 132 >However, some interactive programs can be tested in a
 133       simple fashion reminiscent of batch tests.  For example, prior
 134       to the creation of DejaGnu, the GDB distribution already
 135       included a wide-ranging testing procedure.  This procedure was
 136       very robust, and had already undergone much more debugging and
 137       error checking than many recent DejaGnu test cases.
 138       Accordingly, the best approach was simply to encapsulate the
 139       existing GDB tests, for reporting purposes. Thereafter, new GDB
 140       tests built up a family of Tcl procedures specialized for GDB
 141       testing.</P
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