org.kuali.rice.kns.util
Class AssertionUtils

java.lang.Object
  org.kuali.rice.kns.util.AssertionUtils

public class AssertionUtils
extends Object

This class contains utility methods for making assertions in production code (not test code). Kuali is not using the assert keyword because those assertions are not enabled by default. We can use the methods of this class instead, or throw AssertionError directly. This makes assertions effective in production and development, and avoids any risk of changes to functionality because any side-effects that might be involved in the assertion are done consistently. Although AssertionError can be thrown directly, and sometimes the compiler requires this, in many cases these method invocations will be easier to read than the extra if block with its negated conditional.

These assertions are for use in production code. They should not be confused with Assert, AssertionFailedError, nor org.kuali.test.util.KualiTestAssertionUtils, which are for test code.

These methods should be used such that when they fail and throw AssertionError, it indicates that there is a bug in our software. Drawing attention to the bug this way, as soon as it's discovered, reduces the amount of work required to fix it. So, we should not catch AssertionError (or Throwable) and try to handle or work around it; it indicates a need to change some source code so that the assertion is never false. For more about why, when, and how to use assertions, see Kuali's guide to assertions and Sun's guide to assertions.

See Also:

org.kuali.test.util.KualiTestAssertionUtils

Constructor Summary

AssertionUtils()

Method Summary

static void	assertThat(boolean isTrue) Asserts that the isTrue parameter is true.
static void	assertThat(boolean isTrue, Object detailMessage) Asserts that the isTrue parameter is true, with a detail message.
static void	assertThat(boolean isTrue, String detailMessageFormat, Object... detailMessageArgs) Asserts that the isTrue parameter is true.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

AssertionUtils

public AssertionUtils()

Method Detail

assertThat

public static void assertThat(boolean isTrue)

Asserts that the isTrue parameter is true. If this assertion fails, the AssertionError it throws will have no detail message, only a stacktrace indicating the source file and line number containing the assertion that failed.

This method's name is intended to avoid confusion with JUnit asserts (which are for test code, not production code), and its signature is intended to resemble that of the assert keyword.

Parameters:

isTrue - whether this assertion succeeds. (Boolean objects are auto-unboxed by JDK 1.5.)

Throws:

AssertionError - if isTrue is false

assertThat

public static void assertThat(boolean isTrue,
                              Object detailMessage)

Asserts that the isTrue parameter is true, with a detail message. The purpose of the detail message is to capture and communicate details about the assertion failure that will help a developer diagnose and fix the bug that led this assertion to fail. It's meant to be interpreted in the context of a full stack trace and with the source code containing the failed assertion. It is not a user-level error message. Details like "assertion failed" are redundant, not useful.

This method's name is intended to avoid confusion with JUnit asserts (which are for test code, not production code), and its signature is intended to resemble that of the assert keyword.

Parameters:

isTrue - whether this assertion succeeds. (Boolean objects are auto-unboxed by JDK 1.5.)

detailMessage - value to use for the AssertionError's detail message. If this is an instance of Throwable, then it also becomes the AssertionError's cause. (Primitives are auto-boxed by JDK 1.5.) Objects are converted toString, but only if this assertion fails, so it's better not to convert this detail in advance. The code will be a little easier to read, and there will be some performance improvement (altho it may be insignificant). For example, passing just accountingLine is better than passing accountingLine.toString() or "accounting line:"+accountingLine. Since the assertion has failed, any inconsistent side-effects from the conversion are not an issue. A null reference is treated as the String "null".

Throws:

AssertionError - if isTrue is false

assertThat

public static void assertThat(boolean isTrue,
                              String detailMessageFormat,
                              Object... detailMessageArgs)

Asserts that the isTrue parameter is true. This method is convenient for formatting the detail message, and as an optimization for detail arguments that are expensive to convert to String. For example, suppose foo and bar are two objects with expensive Object.toString() methods. If you use

 AssertionUtils.assertThat(foo.equals(bar), "foo: " + foo + " bar: " + bar);
 

then both object's toString methods will be invoked every time this assertion is done, even though those details are not normally needed because this assertion normally succeeds. You can use this method instead to only do those toString invocations if this assertion fails:

 AssertionUtils.assertThat(foo.equals(bar), "foo: %s bar: %s", foo, bar);
 

This method's name is intended to avoid confusion with JUnit asserts (which are for test code, not production code).

Parameters:

isTrue - whether this assertion succeeds. (Boolean objects are auto-unboxed by JDK 1.5.)

detailMessageFormat - a format string to be used in constructing the AssertionError's detail message. The purpose of this message is to capture and communicate details about the assertion failure that will help a developer diagnose and fix the bug that led the assertion to fail. It's meant to be interpreted in the context of a full stack trace and with the source code containing the failed assertion. It is not a user-level error message. Details like "assertion failed" are redundant, not useful. This detail message cannot be null.

detailMessageArgs - one or more arguments to the format string. Nulls are allowed by some format conversions, such as "%s". (Primitives are auto-boxed by JDK 1.5.) Zero arguments will invoke assertThat(boolean, Object) instead, so the detail message will not be treated as a format string.

Throws:

AssertionError - if isTrue is false

IllegalFormatException - if detailMessageFormat contains an illegal syntax, a format specifier that is incompatible with the given arguments, insufficient arguments given the format string, or other illegal conditions. For specification of all possible formatting errors, see the Details section of Formatter.

NullPointerException - if the detailMessageFormat is null

See Also:

String.format(java.lang.String, java.lang.Object...)