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| 5 | <title>NUnit - EqualConstraint</title>
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| 16 | <div id="header">
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| 17 | <a id="logo" href="http://www.nunit.org"><img src="img/logo.gif" alt="NUnit.org" title="NUnit.org"></a>
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| 18 | <div id="nav">
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| 19 | <a href="http://www.nunit.org">NUnit</a>
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| 20 | <a class="active" href="index.html">Documentation</a>
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| 23 | <!-- End of Header -->
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| 24 |
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| 25 | <div id="content">
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| 26 |
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| 27 | <h2>Equal Constraint (NUnit 2.4 / 2.5)</h2>
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| 28 |
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| 29 | <p>An EqualConstraint is used to test whether an actual value
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| 30 | is equal to the expected value supplied in its constructor,
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| 31 | optionally within a specified tolerance.
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| 32 |
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| 33 | <h4>Constructor</h4>
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| 34 | <div class="code"><pre>
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| 35 | EqualConstraint(object expected )
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| 36 | </pre></div>
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| 37 |
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| 38 | <h4>Syntax</h4>
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| 39 | <div class="code"><pre>
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| 40 | Is.EqualTo( object expected )
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| 41 | </pre></div>
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| 42 |
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| 43 | <h4>Modifiers</h4>
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| 44 | <div class="code"><pre>
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| 45 | ...IgnoreCase
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| 46 | ...AsCollection
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| 47 | ...NoClip
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| 48 | ...Within(object tolerance)
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| 49 | .Ulps
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| 50 | .Percent
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| 51 | .Days
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| 52 | .Hours
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| 53 | .Minutes
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| 54 | .Seconds
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| 55 | .Milliseconds
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| 56 | .Ticks
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| 57 | ...Using(IEqualityComparer comparer)
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| 58 | ...Using(IEqualityComparer<T> comparer)
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| 59 | ...Using(IComparer comparer)
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| 60 | ...Using<T>(IComparer<T> comparer)
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| 61 | ...Using<T>(Comparison<T> comparer)
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| 62 | </pre></div>
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| 63 |
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| 64 | <h4>Comparing Numerics</h4>
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| 65 | <p>Numerics are compared based on their values. Different types
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| 66 | may be compared successfully if their values are equal.
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| 67 |
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| 68 | <p>Using the <b>Within</b> modifier, numerics may be tested
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| 69 | for equality within a fixed or percent tolerance.
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| 70 |
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| 71 | <div class="code"><pre>
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| 72 | Assert.That(2 + 2, Is.EqualTo(4.0));
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| 73 | Assert.That(2 + 2 == 4);
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| 74 | Assert.That(2 + 2, Is.Not.EqualTo(5));
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| 75 | Assert.That(2 + 2 != 5);
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| 76 | Assert.That( 5.0, Is.EqualTo( 5 );
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| 77 | Assert.That( 5.5, Is.EqualTo( 5 ).Within(0.075);
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| 78 | Assert.That( 5.5, Is.EqualTo( 5 ).Within(1.5).Percent;
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| 79 | </pre></div>
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| 80 |
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| 81 | <h4>Comparing Floating Point Values</h4>
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| 82 | <p>Values of type float and double are normally compared using a tolerance
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| 83 | specified by the <b>Within</b> modifier. The special values PositiveInfinity,
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| 84 | NegativeInfinity and NaN compare
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| 85 | as equal to themselves.
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| 86 |
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| 87 | <p>With version 2.5, floating-point values may be compared using a tolerance
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| 88 | in "Units in the Last Place" or ULPs. For certain types of numerical work,
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| 89 | this is safer than a fixed tolerance because it automatically compensates
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| 90 | for the added inaccuracy of larger numbers.
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| 91 |
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| 92 | <div class="code" style="width: 42em"><pre>
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| 93 | Assert.That( 2.1 + 1.2, Is.EqualTo( 3.3 ).Within( .0005 );
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| 94 | Assert.That( double.PositiveInfinity, Is.EqualTo( double.PositiveInfinity ) );
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| 95 | Assert.That( double.NegativeInfinity, Is.EqualTo( double.NegativeInfinity ) );
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| 96 | Assert.That( double.NaN, Is.EqualTo( double.NaN ) );
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| 97 | Assert.That( 20000000000000004.0, Is.EqualTo(20000000000000000.0).Within(1).Ulps);
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| 98 | </pre></div>
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| 99 |
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| 100 | <h4>Comparing Strings</h4>
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| 101 |
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| 102 | <p>String comparisons normally respect case. The <b>IgnoreCase</b> modifier
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| 103 | causes the comparison to be case-insensitive. It may also be used when
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| 104 | comparing arrays or collections of strings.
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| 105 |
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| 106 | <div class="code"><pre>
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| 107 | Assert.That( "Hello!", Is.Not.EqualTo( "HELLO!" ) );
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| 108 | Assert.That( "Hello!", Is.EqualTo( "HELLO!" ).IgnoreCase );
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| 109 |
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| 110 | string[] expected = new string[] { "Hello", World" };
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| 111 | string[] actual = new string[] { "HELLO", "world" };
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| 112 | Assert.That( actual, Is.EqualTo( expected ).IgnoreCase;
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| 113 | </pre></div>
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| 114 |
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| 115 | <h4>Comparing DateTimes and TimeSpans</h4>
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| 116 |
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| 117 | <p><b>DateTimes</b> and <b>TimeSpans</b> may be compared either with or without
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| 118 | a tolerance. A tolerance is specified using <b>Within</b> with either a
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| 119 | <b>TimeSpan</b> as an argument or with a numeric value followed by a one of
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| 120 | the time conversion modifiers: <b>Days</b>, <b>Hours</b>, <b>Minutes</b>,
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| 121 | <b>Seconds</b>, <b>Milliseconds</b> or <b>Ticks</b>.
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| 122 |
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| 123 | <div class="code"><pre>
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| 124 | DateTime now = DateTime.Now;
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| 125 | DateTime later = now + TimeSpan.FromHours(1.0);
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| 126 |
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| 127 | Assert.That( now, Is.EqualTo(now) );
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| 128 | Assert.That( later. Is.EqualTo(now).Within(TimeSpan.FromHours(3.0);
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| 129 | Assert.That( later, Is.EqualTo(now).Within(3).Hours;
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| 130 | </pre></div>
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| 131 |
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| 132 | <h4>Comparing Arrays and Collections</h4>
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| 133 |
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| 134 | <p>Since version 2.2, NUnit has been able to compare two single-dimensioned arrays.
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| 135 | Beginning with version 2.4, multi-dimensioned arrays, nested arrays (arrays of arrays)
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| 136 | and collections may be compared. With version 2.5, any IEnumerable is supported.
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| 137 | Two arrays, collections or IEnumerables are considered equal if they have the
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| 138 | the same dimensions and if each of the corresponding elements is equal.</p>
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| 139 |
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| 140 | <p>If you want to treat two arrays of different shapes as simple collections
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| 141 | for purposes of comparison, use the <b>AsCollection</b> modifier, which causes
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| 142 | the comparison to be made element by element, without regard for the rank or
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| 143 | dimensions of the array. Note that jagged arrays (arrays of arrays) do not
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| 144 | have a single underlying collection. The modifier would be applied
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| 145 | to each array separately, which has no effect in most cases.
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| 146 |
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| 147 | <div class="code"><pre>
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| 148 | int[] i3 = new int[] { 1, 2, 3 };
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| 149 | double[] d3 = new double[] { 1.0, 2.0, 3.0 };
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| 150 | int[] iunequal = new int[] { 1, 3, 2 };
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| 151 | Assert.That(i3, Is.EqualTo(d3));
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| 152 | Assert.That(i3, Is.Not.EqualTo(iunequal));
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| 153 |
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| 154 | int array2x2 = new int[,] { { 1, 2 } { 3, 4 } };
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| 155 | int array4 = new int[] { 1, 2, 3, 4 };
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| 156 | Assert.That( array2x2, Is.Not.EqualTo( array4 ) );
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| 157 | Assert.That( array2x2, Is.EqualTo( array4 ).AsCollection );
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| 158 | </pre></div>
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| 159 |
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| 160 | <h4>Comparing Dictionaries</h4>
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| 161 |
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| 162 | <p>Dictionaries implement <b>ICollection</b>, and NUnit has treated
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| 163 | them as collections since version 2.4. However, this did not
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| 164 | give useful results, since the dictionary entries had to be
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| 165 | in the same order for the comparison to succeed and the
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| 166 | underlying implementation had to be the same.
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| 167 |
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| 168 | <p>Beginning with NUnit 2.5.6, NUnit has specific code for
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| 169 | comparing dictionaries. Two dictionaries are considered equal if
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| 170 |
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| 171 | <ol>
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| 172 | <li>The list of keys is the same - without regard to ordering.
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| 173 | <li>The values associated with each key are equal.
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| 174 | </ol>
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| 175 |
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| 176 | <p>You can use this capability to compare any two objects implementing
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| 177 | <b>IDictionary</b>. Generic and non-generic dictionaries (Hashtables)
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| 178 | may be successfully compared.
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| 179 |
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| 180 | <h4>User-Specified Comparers</h4>
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| 181 |
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| 182 | <p>If the default NUnit or .NET behavior for testing equality doesn't
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| 183 | meet your needs, you can supply a comparer of your own through the
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| 184 | <b>Using</b> modifier. When used with <b>EqualConstraint</b>, you
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| 185 | may supply an <b>IEqualityComparer</b>, <b>IEqualityComparer<T></b>,
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| 186 | <b>IComparer</b>, <b>IComparer<T></b>; or <b>Comparison<T></b>
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| 187 | as the argument to <b>Using</b>.
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| 188 |
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| 189 | <div class="code"><pre>
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| 190 | Assert.That( myObj1, Is.EqualTo( myObj2 ).Using( myComparer ) );
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| 191 | </pre></div>
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| 192 |
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| 193 | <h4>Notes</h4>
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| 194 | <ol>
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| 195 | <li><p>When checking the equality of user-defined classes, NUnit makes use
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| 196 | of the <b>Equals</b> override on the expected object. If you neglect to
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| 197 | override <b>Equals</b>, you can expect failures non-identical objects.
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| 198 | In particular, overriding <b>operator==</b> without overriding <b>Equals</b>
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| 199 | has no effect.
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| 200 | <li><p>The <b>Within</b> modifier was originally designed for use with floating point
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| 201 | values only. Beginning with NUnit 2.4, comparisons of <b>DateTime</b> values
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| 202 | may use a <b>TimeSpan</b> as a tolerance. Beginning with NUnit 2.4.2,
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| 203 | non-float numeric comparisons may also specify a tolerance.
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| 204 | <li><p>Beginning with NUnit 2.4.4, float and double comparisons for which no
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| 205 | tolerance is specified use a default, use the value of
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| 206 | <b>GlobalSettings.DefaultFloatingPointTolerance</b>. If this is not
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| 207 | set, a tolerance of 0.0d is used.
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| 208 | <li><p>Prior to NUnit 2.2.3, comparison of two NaN values would always fail,
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| 209 | as specified by IEEE floating point standards. The new behavior, was
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| 210 | introduced after some discussion becuase it seems more useful in tests.
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| 211 | To avoid confusion, consider using <b>Is.NaN</b> where appropriate.
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| 212 | <li><p>When an equality test between two strings fails, the relevant portion of
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| 213 | of both strings is displayed in the error message, clipping the strings to
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| 214 | fit the length of the line as needed. Beginning with 2.4.4, this behavior
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| 215 | may be modified by use of the <b>NoClip</b> modifier on the constraint. In
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| 216 | addition, the maximum line length may be modified for all tests by setting
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| 217 | the value of <b>TextMessageWriter.MaximumLineLength</b> in the appropriate
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| 218 | level of setup.
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| 219 | <li><p>When used with arrays, collections or dictionaries, EqualConstraint
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| 220 | operates recursively. Any modifiers are saved and used as they apply to
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| 221 | individual items.
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| 222 | <li><p>A user-specified comparer will not be called by <b>EqualConstraint</b>
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| 223 | if either or both arguments are null. If both are null, the Constraint
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| 224 | succeeds. If only one is null, it fails.
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| 225 | <li><p>NUnit has special semantics for comparing <b>Streams</b> and
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| 226 | <b>DirectoryInfos</b>. For a <b>Stream</b>, the contents are compared.
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| 227 | For a <b>DirectoryInfo</b>, the first-level directory contents are compared.
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| 228 | </ol>
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| 229 |
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| 230 | </div>
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| 231 |
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| 232 | <!-- Submenu -->
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| 233 | <div id="subnav">
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| 234 | <ul>
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| 235 | <li><a href="index.html">NUnit 2.5.10</a></li>
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| 236 | <ul>
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| 237 | <li><a href="getStarted.html">Getting Started</a></li>
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| 238 | <li><a href="assertions.html">Assertions</a></li>
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| 239 | <li><a href="constraintModel.html">Constraints</a></li>
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| 240 | <ul>
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| 241 | <li id="current"><a href="equalConstraint.html">Equal Constraint</a></li>
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| 242 | <li><a href="sameasConstraint.html">SameAs Constraint</a></li>
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| 243 | <li><a href="conditionConstraints.html">Condition Constraints</a></li>
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| 244 | <li><a href="comparisonConstraints.html">Comparison Constrants</a></li>
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| 245 | <li><a href="pathConstraints.html">Path Constraints</a></li>
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| 246 | <li><a href="typeConstraints.html">Type Constraints</a></li>
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| 247 | <li><a href="stringConstraints.html">String Constraints</a></li>
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| 248 | <li><a href="collectionConstraints.html">Collection Constraints</a></li>
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| 249 | <li><a href="propertyConstraint.html">Property Constraint</a></li>
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| 250 | <li><a href="throwsConstraint.html">Throws Constraint</a></li>
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| 251 | <li><a href="compoundConstraints.html">Compound Constraints</a></li>
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| 252 | <li><a href="delayedConstraint.html">Delayed Constraint</a></li>
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| 253 | <li><a href="listMapper.html">List Mapper</a></li>
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| 254 | <li><a href="reusableConstraint.html">Reusable Constraint</a></li>
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| 255 | </ul>
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| 256 | <li><a href="attributes.html">Attributes</a></li>
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| 257 | <li><a href="runningTests.html">Running Tests</a></li>
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| 270 | Copyright © 2010 Charlie Poole. All Rights Reserved.
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