<?xml version="1.0" encoding="utf-8" ?> <!DOCTYPE fileref SYSTEM "fileref.dtd"> <fileref> <header> <copyright> <year>2012</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. </legalnotice> <title>assert.hrl</title> <prepared></prepared> <docno></docno> <date></date> <rev></rev> </header> <file>assert.hrl.xml</file> <filesummary>Assert macros.</filesummary> <description> <p>The include file <c>assert.hrl</c> provides macros for inserting assertions in your program code.</p> <p>Include the following directive in the module from which the function is called:</p> <code type="none"> -include_lib("stdlib/include/assert.hrl").</code> <p>When an assertion succeeds, the assert macro yields the atom <c>ok</c>. When an assertion fails, an exception of type <c>error</c> is generated. The associated error term has the form <c>{Macro, Info}</c>. <c>Macro</c> is the macro name, for example, <c>assertEqual</c>. <c>Info</c> is a list of tagged values, such as <c>[{module, M}, {line, L}, ...]</c>, which gives more information about the location and cause of the exception. All entries in the <c>Info</c> list are optional; do not rely programatically on any of them being present.</p> <p>If the macro <c>NOASSERT</c> is defined when <c>assert.hrl</c> is read by the compiler, the macros are defined as equivalent to the atom <c>ok</c>. The test is not performed and there is no cost at runtime.</p> <p>For example, using <c>erlc</c> to compile your modules, the following disable all assertions:</p> <code type="none"> erlc -DNOASSERT=true *.erl</code> <p>The value of <c>NOASSERT</c> does not matter, only the fact that it is defined.</p> <p>A few other macros also have effect on the enabling or disabling of assertions:</p> <list type="bulleted"> <item><p>If <c>NODEBUG</c> is defined, it implies <c>NOASSERT</c>, unless <c>DEBUG</c> is also defined, which is assumed to take precedence.</p> </item> <item><p>If <c>ASSERT</c> is defined, it overrides <c>NOASSERT</c>, that is, the assertions remain enabled.</p></item> </list> <p>If you prefer, you can thus use only <c>DEBUG</c>/<c>NODEBUG</c> as the main flags to control the behavior of the assertions (which is useful if you have other compiler conditionals or debugging macros controlled by those flags), or you can use <c>ASSERT</c>/<c>NOASSERT</c> to control only the assert macros.</p> </description> <section> <title>Macros</title> <taglist> <tag><c>assert(BoolExpr)</c></tag> <item> <p>Tests that <c>BoolExpr</c> completes normally returning <c>true</c>.</p> </item> <tag><c>assertNot(BoolExpr)</c></tag> <item> <p>Tests that <c>BoolExpr</c> completes normally returning <c>false</c>.</p> </item> <tag><c>assertMatch(GuardedPattern, Expr)</c></tag> <item> <p>Tests that <c>Expr</c> completes normally yielding a value that matches <c>GuardedPattern</c>, for example:</p> <code type="none"> ?assertMatch({bork, _}, f())</code> <p>Notice that a guard <c>when ...</c> can be included:</p> <code type="none"> ?assertMatch({bork, X} when X > 0, f())</code> </item> <tag><c>assertNotMatch(GuardedPattern, Expr)</c></tag> <item> <p>Tests that <c>Expr</c> completes normally yielding a value that does not match <c>GuardedPattern</c>.</p> <p>As in <c>assertMatch</c>, <c>GuardedPattern</c> can have a <c>when</c> part.</p> </item> <tag><c>assertEqual(ExpectedValue, Expr)</c></tag> <item> <p>Tests that <c>Expr</c> completes normally yielding a value that is exactly equal to <c>ExpectedValue</c>.</p> </item> <tag><c>assertNotEqual(ExpectedValue, Expr)</c></tag> <item> <p>Tests that <c>Expr</c> completes normally yielding a value that is not exactly equal to <c>ExpectedValue</c>.</p> </item> <tag><c>assertException(Class, Term, Expr)</c></tag> <item> <p>Tests that <c>Expr</c> completes abnormally with an exception of type <c>Class</c> and with the associated <c>Term</c>. The assertion fails if <c>Expr</c> raises a different exception or if it completes normally returning any value.</p> <p>Notice that both <c>Class</c> and <c>Term</c> can be guarded patterns, as in <c>assertMatch</c>.</p> </item> <tag><c>assertNotException(Class, Term, Expr)</c></tag> <item> <p>Tests that <c>Expr</c> does not evaluate abnormally with an exception of type <c>Class</c> and with the associated <c>Term</c>. The assertion succeeds if <c>Expr</c> raises a different exception or if it completes normally returning any value.</p> <p>As in <c>assertException</c>, both <c>Class</c> and <c>Term</c> can be guarded patterns.</p> </item> <tag><c>assertError(Term, Expr)</c></tag> <item> <p>Equivalent to <c>assertException(error, Term, Expr)</c></p> </item> <tag><c>assertExit(Term, Expr)</c></tag> <item> <p>Equivalent to <c>assertException(exit, Term, Expr)</c></p> </item> <tag><c>assertThrow(Term, Expr)</c></tag> <item> <p>Equivalent to <c>assertException(throw, Term, Expr)</c></p> </item> </taglist> </section> <section> <title>See Also</title> <p><seealso marker="compiler:compile"><c>compile(3)</c></seealso>, <seealso marker="erts:erlc"><c>erlc(3)</c></seealso></p> </section> </fileref>