1 // ***********************************************************************
2 // Copyright (c) 2007 Charlie Poole
4 // Permission is hereby granted, free of charge, to any person obtaining
5 // a copy of this software and associated documentation files (the
6 // "Software"), to deal in the Software without restriction, including
7 // without limitation the rights to use, copy, modify, merge, publish,
8 // distribute, sublicense, and/or sell copies of the Software, and to
9 // permit persons to whom the Software is furnished to do so, subject to
10 // the following conditions:
12 // The above copyright notice and this permission notice shall be
13 // included in all copies or substantial portions of the Software.
15 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
18 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
19 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
20 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
21 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
22 // ***********************************************************************
25 #define NUNIT_FRAMEWORK
29 namespace NUnit.Framework.Constraints
32 /// EmptyConstraint tests a whether a string or collection is empty,
33 /// postponing the decision about which test is applied until the
34 /// type of the actual argument is known.
36 public class EmptyConstraint : Constraint
38 private Constraint realConstraint;
41 /// The Description of what this constraint tests, for
42 /// use in messages and in the ConstraintResult.
44 public override string Description
46 get { return realConstraint == null ? "<empty>" : realConstraint.Description; }
50 /// Test whether the constraint is satisfied by a given value
52 /// <param name="actual">The value to be tested</param>
53 /// <returns>True for success, false for failure</returns>
54 public override ConstraintResult ApplyTo<TActual>(TActual actual)
56 // NOTE: actual is string will fail for a null typed as string
57 if (typeof(TActual) == typeof(string))
58 realConstraint = new EmptyStringConstraint();
59 else if (actual == null)
60 throw new System.ArgumentException("The actual value must be a string or a non-null IEnumerable or DirectoryInfo", "actual");
61 #if !SILVERLIGHT && !PORTABLE
62 else if (actual is System.IO.DirectoryInfo)
63 realConstraint = new EmptyDirectoryConstraint();
66 realConstraint = new EmptyCollectionConstraint();
68 return realConstraint.ApplyTo(actual);