#PowerAssert.NET

Readable, Writable Test Assertions for .NET

A .NET port of Groovy's PowerAssert. It prints an easy-to-understand decomposition of your assertion s expression tree (with values) whenever an assertion fails.

Examples:

Seeing actual values

Given the following unit test:

[Test]
public void RunComplexExpression()
{
   int x = 11;
   int y = 6;
   DateTime d = new DateTime(2010, 3, 1);
   PAssert.IsTrue(() => x + 5 == d.Month * y);
}

PowerAssert will cause a failure with the following message:

System.Exception : IsTrue failed, expression was:

x + 5 == d.Month * y
. .   __ . .   . . .
. .   |  . .   . . .
. |   |  . \_ _/ | .
| |   |  .   |   | |
| |   |  |   |   | 6
| |   |  |   |   18
| |   |  |   3
| |   |  1/03/2010 12:00:00 a.m.
| |   False
| 16
11

Looking into collections

PowerAssert gives you insights into the contents of your collections under assertion:

Given the following unit test:

[Test]
[Ignore("This test will fail for demo purposes")]
public void PrintingLinqExpressionStatements()
{
    var list = Enumerable.Range(0, 150);
    PAssert.IsTrue(() => (from l in list where l % 2 == 0 select l).Sum() == 0);
}

PowerAssert will cause a failure with the following message:

System.Exception : IsTrue failed, expression was:

list.Where(l => ((l % 2) == 0)).Sum() == 0
.  . .   .                      . .   __
.  . .   .                      \ /   |
.  . \_ _/                       |    |
\ _/   |                         |    |
 |     |                         |    False
 |     |                         5550
 |     [0, 2, 4, 6, 8, ...]
 [0, 1, 2, 3, 4, ...]

Equals versus ==

Given the following unit test:

[Test]
public void EqualsButNotOperatorEquals()
{
    var t1 = new Tuple<string>("foo");
    var t2 = new Tuple<string>("foo");

    PAssert.IsTrue(() => t1 == t2);
}

Power Assert will cause a failure with the following message:

System.Exception : IsTrue failed, expression was:

t1 == t2
.. __ ..
__ |  __
|  |  (foo)
|  False, but would have been True with Equals()
(foo)

Equals versus SequenceEquals

Given the following unit test:

[Test]
[Ignore("This test will fail for demo purposes")]
public void SequenceEqualButNotOperatorEquals()
{
    object list = new List<int> { 1, 2, 3 };
    object array = new[] { 1, 2, 3 };
    PAssert.IsTrue(() => list == array);
}

Power Assert will cause a failure with the following message:

System.Exception : IsTrue failed, expression was:

list == array
.  . __ .   .
\ _/ |  \_ _/
 |   |    [1, 2, 3]
 |   False, but would have been True with .SequenceEqual()
 [1, 2, 3]

Contributing

Feature requests and PRs are welcomed!

Forked from http://powerassert.codeplex.com/SourceControl/changeset/8e1d4d6874e1