Substring Constraint

SubstringConstraint tests for a substring.

Constructor

SubstringConstraint(string expected)

Syntax

Does.Contain(string expected)

Modifiers

...IgnoreCase
...Using(StringComparison comparisonType)
...Using(CultureInfo culture)

Examples of Use

[Test]
public void StringConstraint_Examples()
{
    Assert.That("Hello World!", Does.StartWith("Hello"));
    Assert.That("Hello World!", Does.EndWith("World!"));
    Assert.That("Hello World!", Does.Contain("lo Wor"));
    Assert.That("Hello World!", Does.Match("H.*!"));
}

Specifying a StringComparison

Assert.That("Hello World!", Does.Contain("WORLD").Using(StringComparison.OrdinalIgnoreCase));
Assert.That("Hello World!", Does.Contain("World").Using(StringComparison.Ordinal));

Specifying a CultureInfo

The Using(CultureInfo) modifier allows for culture-specific string comparisons. It can be combined with .IgnoreCase for case-insensitive culture-aware comparisons:

// Using Turkish culture where 'i' and 'I' have special casing rules
Assert.That("Hello TITLE World", Does.Contain("title").IgnoreCase.Using(new CultureInfo("tr-TR")));

// Culture-specific comparison without case-insensitivity
Assert.That("Straße Street", Does.Contain("Straße").Using(new CultureInfo("de-DE")));

Notes

1. Only one Using modifier may be specified. Attempting to use multiple Using modifiers will throw an InvalidOperationException.