Shuttle.Core.Contract

A guard implementation that performs assertions/assumptions to prevent invalid code execution.

Installation

dotnet add package Shuttle.Core.Contract

Guard

void Against<TException>(bool condition, string message) where TException : Exception

Throws exception TException with the given message if the condition is true. If exception type TException does not have a constructor that accepts a message then an InvalidOperationException is thrown instead.

Guard.Against<ArgumentException>(age < 0, "Age cannot be negative");

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string AgainstEmpty(string? value, [CallerArgumentExpression("value")] string? name = null)

Throws a ArgumentNullException if the given value is null or empty/whitespace; else returns the value.

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Guid AgainstEmpty(Guid value, [CallerArgumentExpression("value")] string? name = null)

Throws an ArgumentException when the value is equal to an empty Guid ({00000000-0000-0000-0000-000000000000}); else returns the value.

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IEnumerable<T> AgainstEmpty<T>(IEnumerable<T> enumerable, [CallerArgumentExpression("enumerable")] string? name = null)

Throws a ArgumentNullException if the given enumerable is null, or an ArgumentException if the enumerable does not contain any entries; else returns the enumerable.

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T AgainstNull<T>(T? value, [CallerArgumentExpression("value")] string? name = null)

Throws a ArgumentNullException if the given value is null; else returns the value.

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TEnum AgainstUndefinedEnum<TEnum>(object? value, [CallerArgumentExpression("value")] string? name = null)

Throws an InvalidOperationException if the provided value cannot be found in the given TEnum; else returns the value as TEnum. Accepts both enum values and string representations.

Usage Examples

// Basic null checking
var name = Guard.AgainstNull(userName); // Throws ArgumentNullException if userName is null
var email = Guard.AgainstNull(userEmail, nameof(userEmail)); // Exception message includes parameter name

// String validation
var password = Guard.AgainstEmpty(userPassword); // Throws ArgumentNullException if null, empty, or whitespace
var title = Guard.AgainstEmpty(documentTitle, nameof(documentTitle)); // Includes parameter name in exception

// Collection validation
var items = Guard.AgainstEmpty(orderItems, nameof(orderItems)); // Throws if null or empty

// Custom assertions
Guard.Against<ArgumentException>(userId > 0, "User ID must be positive"); // Throws ArgumentException if condition is false

// Enum validation
var status = Guard.AgainstUndefinedEnum<OrderStatus>("Pending", nameof(status)); // Converts string to enum or throws

Throws exception TException with the given message if the assertion is false. If exception type TException does not have a constructor that accepts a message then an InvalidOperationException is thrown instead.

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string AgainstEmpty(string? value, [CallerArgumentExpression("value")] string? name = null)

Throws a ArgumentNullException if the given value is null or empty/whitespace; else returns the value.

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Guid AgainstEmpty(Guid value, [CallerArgumentExpression("value")] string? name = null)

Throws and ArgumentException when the value is equal to an empty Guid ({00000000-0000-0000-0000-000000000000}); else returns the value.

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IEnumerable<T> AgainstEmpty<T>(IEnumerable<T> enumerable, [CallerArgumentExpression("enumerable")] string? name = null)

Throws an ArgumentException if the given enumerable does not contain any entries; else returns the enumerable.

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T AgainstNull<T>(T? value, [CallerArgumentExpression("value")] string? name = null)

Throws a ArgumentNullException if the given value is null; else returns the value.

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TEnum AgainstUndefinedEnum<TEnum>(object? value, [CallerArgumentExpression("value")] string? name = null)

Throws an InvalidOperationException if the provided value cannot be found in the given TEnum; else returns the value as TEnum.