rspec/rules/S3065/rule.adoc

== Why is this an issue?

When using ``++Math.min()++`` and ``++Math.max()++`` together for bounds checking, it's important to feed the right operands to each method. ``++Math.min()++`` should be used with the *upper* end of the range being checked, and ``++Math.max()++`` should be used with the *lower* end of the range. Get it backwards, and the result will always be the same end of the range.


=== Noncompliant code example

[source,text]
----
  private static final int UPPER = 20;
  private static final int LOWER = 0;

  public int doRangeCheck(int num) {    // Let's say num = 12
    int result = Math.min(LOWER, num);  // result = 0
    return Math.max(UPPER, result);     // Noncompliant; result is now 20: even though 12 was in the range
  }
----


=== Compliant solution

Swapping method ``++min()++`` and ``++max()++`` invocations without changing parameters.

[source,text]
----
  private static final int UPPER = 20;
  private static final int LOWER = 0;

  public int doRangeCheck(int num) {    // Let's say num = 12
    int result = Math.max(LOWER, num);  // result = 12
    return Math.min(UPPER, result);     // Compliant; result is still 12
  }
----

or swapping bounds ``++UPPER++`` and ``++LOWER++`` used as parameters without changing the invoked methods.


[source,text]
----
  private static final int UPPER = 20;
  private static final int LOWER = 0;

  public int doRangeCheck(int num) {    // Let's say num = 12
    int result = Math.min(UPPER, num);  // result = 12
    return Math.max(LOWER, result);     // Compliant; result is still 12
  }
----