Char

Describes the possible expectations for char values.

Expectation	Negated	Summary
IsEqualTo	IsNotEqualTo	equal to the expected character
IsOneOf	IsNotOneOf	equal to one of the expected characters
IsAnAsciiLetter	IsNotAnAsciiLetter	an ASCII letter
IsAnAsciiDigit	IsNotAnAsciiDigit	an ASCII digit
IsAnAsciiHexDigit	IsNotAnAsciiHexDigit	an ASCII hexadecimal digit
IsALetter	IsNotALetter	a Unicode letter
IsADigit	IsNotADigit	a decimal digit
IsANumber	IsNotANumber	a Unicode number
IsUpperCased	IsNotUpperCased	an upper-case letter
IsLowerCased	IsNotLowerCased	a lower-case letter
IsAControlCharacter	IsNotAControlCharacter	a control character
IsWhiteSpace	IsNotWhiteSpace	whitespace

.NET 8 or later

On .NET 8 or later char is an INumber<char>, so the ordering expectations, IsBetween, IsPositive and IsNegative of the number expectations also accept a char. Below .NET 8 they are not available for char.

Equality

You can verify that the char is equal to another one or not:

char initial = 'a';

await That(initial).IsEqualTo('a');
await That(initial).IsNotEqualTo('b');
await That(initial).IsEqualTo('A').IgnoringCase();

One of

You can verify that the char is one of many alternatives:

char initial = 'a';

await That(initial).IsOneOf('a', 'b', 'c');
await That(initial).IsNotOneOf('x', 'y', 'z');
await That(initial).IsOneOf('A', 'B', 'C').IgnoringCase();

Categories

You can verify the category of the char, or that it does not belong to it:

await That('a').IsAnAsciiLetter();
await That('乐').IsALetter();
await That('3').IsADigit();
await That('½').IsANumber().And.IsNotADigit();
await That('A').IsUpperCased();
await That('\t').IsWhiteSpace().And.IsAControlCharacter();
await That(' ').IsNotAControlCharacter();

Each expectation follows the corresponding method of char:

Expectation	Method
IsAnAsciiLetter	char.IsAsciiLetter
IsAnAsciiDigit	char.IsAsciiDigit
IsAnAsciiHexDigit	char.IsAsciiHexDigit
IsALetter	char.IsLetter
IsADigit	char.IsDigit
IsANumber	char.IsNumber
IsUpperCased	char.IsUpper
IsLowerCased	char.IsLower
IsAControlCharacter	char.IsControl
IsWhiteSpace	char.IsWhiteSpace

IsADigit only accepts decimal digits, while IsANumber also accepts characters like '½'.

Casing of a char vs. a string

IsUpperCased and IsLowerCased differ from the string casing expectations, which only look at cased letters: '1' is neither upper-cased nor lower-cased, while "1" is both.

IgnoringCase() compares the characters the same way as strings with IgnoringCase(), i.e. with StringComparison.OrdinalIgnoreCase.