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The assert() statement is a convenient mechanism for incorporating diagnostic tests in code. Expressions used with the standard assert statement should not contain side effects. Typically, the The behavior of the assert statement depends on the status of a runtime property. If When enabled, the assert statement is designed to evaluate evaluates its expression argument and throw throws an AssertionError if the result of the expression is convertible to false. If When disabled, assert is defined to be a no-operation. Consequently, op; any side effects resulting from evaluation of the expression in the assertion are lost in production quality code. Consequently, expressions used with the standard assert statement must not produce side effects.

Noncompliant Code Example

This noncompliant code example demonstrates an action being carried out in an assertion. The idea is attempts to delete all the null names from the list , howeverin an assertion. However, the boolean Boolean expression is unexpectedly not evaluated when assertions are disabled.

private ArrayList<String> names;

void process(int index) {
  assert names.remove(null); // sideSide effect 
  // ...
}

Compliant Solution

Avoid the The possibility of side effects in assertions . This can be achieved avoided by decoupling the boolean Boolean expression from the assertion.:

private ArrayList<String> names;

void process(int index) {
  boolean nullsRemoved = names.remove(null);
  assert nullsRemoved; // noNo side effect 
  // ... 
}

Risk Assessment

Side effects in assertions can lead to unexpected and erroneous behavior.result in program behavior that depends on whether assertions are enabled or disabled.

Related Vulnerabilities

Search for vulnerabilities resulting from the violation of this guideline on the CERT website.

Other Languages

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Automated Detection

Automated detection of assertion operands that contain locally visible side effects is straightforward. Some analyses could require programmer assistance to determine which method invocations lack side effects.

Related Guidelines

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Android Implementation Details

The assert statement is supported on the Dalvik VM but is ignored under the default configuration. Assertions may be enabled by setting the system property debug.assert via: adb shell setprop debug.assert 1 or by sending the command-line argument --enable-assert to the Dalvik VM. assertions.This guideline appears in the C++ Coding Standard as EXP31-CPP. Avoid side effects in assertions.

Bibliography

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]	Programming With Assertions
[Seacord 2015]	Image Added IDS17-J. Prevent XML External Entity Attacks LiveLesson

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Image Added Image Added Image AddedEXP09-J. Do not depend on operator precedence while using expressions containing side-effects      04. Expressions (EXP)      EXP11-J. Be careful of autoboxing when removing elements from a Collection