NUnit - ComparisonConstraints

## Comparison Constraints (NUnit 2.4 / 2.5)

Comparison constraints are able to test whether one value is greater or less than another. Comparison constraints work on numeric values, as well as other objects that implement the IComparable interface or - beginning with NUnit 2.5 - IComparable<T>.

Beginning with NUnit 2.5, you may supply your own comparison algorithm through the Using modifier.

### GreaterThanConstraint

#### Action

Tests that one value is greater than another.

#### Constructor

    GreaterThanConstraint(object expected)

#### Syntax

    Is.GreaterThan(object expected)
    Is.Positive // Equivalent to Is.GreaterThan(0)

#### Modifiers

    ...Using(IComparer comparer)
    ...Using(IComparer<T> comparer)
    ...Using(Comparison<T> comparer)

#### Examples of Use

    Assert.That(7, Is.GreaterThan(3));
    Assert.That(myOwnObject,
        Is.GreaterThan(theExpected).Using(myComparer));
    Assert.That(42, Is.Positive);

### GreaterThanOrEqualConstraint

#### Action

Tests that one value is greater than or equal to another.

#### Constructor

    GreaterThanOrEqualConstraint(object expected)

#### Syntax

    Is.GreaterThanOrEqualTo(object expected)
    Is.AtLeast(object expected)

#### Modifiers

    ...Using(IComparer comparer)
    ...Using(IComparer<T> comparer)
    ...Using(Comparison<T> comparer)

#### Examples of Use

    Assert.That(7, Is.GreaterThanOrEqualTo(3));
    Assert.That(7, Is.AtLeast(3));
    Assert.That(7, Is.GreaterThanOrEqualTo(7));
    Assert.That(7, Is.AtLeast(7));
    Assert.That(myOwnObject,
        Is.GreaterThanOrEqualTo(theExpected).Using(myComparer));

### LessThanConstraint

#### Action

Tests that one value is less than another.

#### Constructor

    LessThanConstraint(object expected)

#### Syntax

    Is.LessThan(object expected)
    Is.Negative // Equivalent to Is.LessThan(0)

#### Modifiers

    ...Using(IComparer comparer)
    ...Using(IComparer<T> comparer)
    ...Using(Comparison<T> comparer)

#### Examples of Use

    Assert.That(3, Is.LessThan(7));
    Assert.That(myOwnObject,
        Is.LessThan(theExpected).Using(myComparer));
    Assert.That(-5, Is.Negative);

### LessThanOrEqualConstraint

#### Action

Tests that one value is less than or equal to another.

#### Constructor

    LessThanOrEqualConstraint(object expected)

#### Syntax

    Is.LessThanOrEqualTo(object expected)
    Is.AtMost(object expected)

#### Modifiers

    ...Using(IComparer comparer)
    ...Using(IComparer<T> comparer)
    ...Using(Comparison<T> comparer)

#### Examples of Use

    Assert.That(3, Is.LessThanOrEqualTo(7));
    Assert.That(3, Is.AtMost(7));
    Assert.That(3, Is.LessThanOrEqualTo(3));
    Assert.That(3, Is.AtMost(3));
    Assert.That(myOwnObject,
        Is.LessThanOrEqualTo(theExpected).Using(myComparer));

### RangeConstraint

#### Action

#### Constructor

    RangeConstraint(IComparable from, IComparable to)

#### Syntax

    Is.InRange(IComparable from, IComparable to)

#### Modifiers

    ...Using(IComparer comparer)
    ...Using(IComparer<T> comparer)
    ...Using(Comparison<T> comparer)

#### Examples of Use

    int[] iarray = new int[] { 1, 2, 3 }

    Assert.That( 42, Is.InRange(1, 100) );
    Assert.That( iarray, Is.All.InRange(1, 3) );
    Assert.That(myOwnObject,
        Is.InRange(lowExpected, highExpected).Using(myComparer));