Null checks

src/BBT.StructureTools/BBT.StructureTools.csproj

@@ -24,9 +24,7 @@
   <ItemGroup>
     <PackageReference Include="BBT.Maybe" Version="2.0.0" />
     <PackageReference Include="BBT.StrategyPattern" Version="1.0.0" />
-    <PackageReference Include="FluentAssertions" Version="5.9.0">
-      <PrivateAssets>all</PrivateAssets>
-    </PackageReference>
+    <PackageReference Include="FluentAssertions" Version="5.9.0" />
     <PackageReference Include="Microsoft.CodeAnalysis.FxCopAnalyzers" Version="2.9.4">
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>

src/BBT.StructureTools/Extension/StructureToolsArgumentChecks.cs

@@ -0,0 +1,143 @@
+namespace BBT.StructureTools.Extension
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Diagnostics;
+    using System.Linq;
+
+    /// <summary>
+    /// Common runtime checks that throw <see cref="ArgumentException"/> upon failure.
+    /// </summary>
+    public static class StructureToolsArgumentChecks
+    {
+        /// <summary>
+        /// Throws an exception if the specified parameter's value is null.
+        /// </summary>
+        /// <typeparam name="T">The type of the parameter.</typeparam>
+        /// <param name="value">The value of the argument.</param>
+        /// <param name="parameterName">The name of the parameter to include in any thrown exception.</param>
+        /// <exception cref="ArgumentNullException">Thrown if <paramref name="value"/> is <c>null</c>.</exception>
+        [DebuggerStepThrough]
+        public static void NotNull<T>([ValidatedNotNull]this T value, string parameterName)
+            where T : class
+        {
+            if (value == null)
+            {
+                throw new ArgumentNullException(parameterName);
+            }
+        }
+
+        /// <summary>
+        /// Throws an exception if the specified parameter's value is null, empty or consists only of white-space characters.
+        /// </summary>
+        /// <param name="value">The value of the argument.</param>
+        /// <param name="parameterName">The name of the parameter to include in any thrown exception.</param>
+        /// <exception cref="ArgumentNullException">Thrown if <paramref name="value"/> is <c>null</c>.</exception>
+        /// <exception cref="ArgumentOutOfRangeException">Thrown if <paramref name="value"/> is empty or consists only of white-space characters.</exception>
+        [DebuggerStepThrough]
+        public static void NotNullOrWhiteSpace([ValidatedNotNull]this string value, string parameterName)
+        {
+            if (value == null)
+            {
+                throw new ArgumentNullException(parameterName);
+            }
+
+            if (string.IsNullOrWhiteSpace(value))
+            {
+                throw new ArgumentOutOfRangeException(parameterName);
+            }
+        }
+
+        /// <summary>
+        /// Throws an exception if the specified parameter's value is negative.
+        /// </summary>
+        /// <param name="value">The value of the argument.</param>
+        /// <param name="parameterName">The name of the parameter to include in any thrown exception.</param>
+        /// <exception cref="ArgumentOutOfRangeException">Thrown if <paramref name="value"/> is negative.</exception>
+        [DebuggerStepThrough]
+        public static void NotNegative(this int value, string parameterName)
+        {
+            if (value < 0)
+            {
+                throw new ArgumentOutOfRangeException(parameterName);
+            }
+        }
+
+        /// <summary>
+        /// Throws an exception if the specified parameter's value is negative or zero.
+        /// </summary>
+        /// <param name="value">The value of the argument.</param>
+        /// <param name="parameterName">The name of the parameter to include in any thrown exception.</param>
+        /// <exception cref="ArgumentOutOfRangeException">Thrown if <paramref name="value"/> is negative or zero.</exception>
+        [DebuggerStepThrough]
+        public static void NotNegativeOrZero(this int value, string parameterName)
+        {
+            if (value <= 0)
+            {
+                throw new ArgumentOutOfRangeException(parameterName);
+            }
+        }
+
+        /// <summary>
+        /// Throws an exception if the specified parameter's value is null or empty.
+        /// </summary>
+        /// <typeparam name="T">The type of the parameter.</typeparam>
+        /// <param name="value">The value of the argument.</param>
+        /// <param name="parameterName">The name of the parameter to include in any thrown exception.</param>
+        /// <exception cref="ArgumentNullException">Thrown if <paramref name="value"/> is <c>null</c>.</exception>
+        /// <exception cref="ArgumentException">Thrown if <paramref name="value"/> is empty.</exception>
+        [DebuggerStepThrough]
+        public static void NotNullOrEmpty<T>(this IEnumerable<T> value, string parameterName)
+        {
+            // ReSharper disable once PossibleMultipleEnumeration
+            value.NotNull(parameterName);
+
+            // ReSharper disable once PossibleMultipleEnumeration
+            if (!value.Any())
+            {
+                throw new ArgumentException("Empty list.", parameterName);
+            }
+        }
+
+        /// <summary>
+        /// Throws an exception if the specified parameter's value is null, empty or contains an empty element.
+        /// </summary>
+        /// <typeparam name="T">The type of the parameter.</typeparam>
+        /// <param name="value">The value of the argument.</param>
+        /// <param name="parameterName">The name of the parameter to include in any thrown exception.</param>
+        /// <exception cref="ArgumentNullException">Thrown if <paramref name="value"/> is <c>null</c>.</exception>
+        /// <exception cref="ArgumentException">Thrown if <paramref name="value"/> is empty.</exception>
+        /// <exception cref="ArgumentOutOfRangeException">Thrown if <paramref name="value"/> contains an empty element.</exception>
+        [DebuggerStepThrough]
+        public static void NotNullOrEmptyElement<T>(this IEnumerable<T> value, string parameterName)
+        {
+            // ReSharper disable once PossibleMultipleEnumeration
+            value.NotNull(parameterName);
+
+            // ReSharper disable once PossibleMultipleEnumeration
+            if (value.Any(x => x == null))
+            {
+                throw new ArgumentOutOfRangeException(parameterName, "List contains.");
+            }
+        }
+
+        /// <summary>
+        /// Throws an exception if the specified parameter's value is null, empty or contains an empty element.
+        /// </summary>
+        /// <typeparam name="T">The type of the parameter.</typeparam>
+        /// <param name="value">The value of the argument.</param>
+        /// <param name="parameterName">The name of the parameter to include in any thrown exception.</param>
+        /// <exception cref="ArgumentNullException">Thrown if <paramref name="value"/> is <c>null</c>.</exception>
+        /// <exception cref="ArgumentException">Thrown if <paramref name="value"/> is empty.</exception>
+        /// <exception cref="ArgumentOutOfRangeException">Thrown if <paramref name="value"/> contains an empty element.</exception>
+        [DebuggerStepThrough]
+        public static void NotNullOrEmptyOrEmptyElement<T>(this IEnumerable<T> value, string parameterName)
+        {
+            // ReSharper disable once PossibleMultipleEnumeration
+            value.NotNullOrEmpty(parameterName);
+
+            // ReSharper disable once PossibleMultipleEnumeration
+            value.NotNullOrEmptyElement(parameterName);
+        }
+    }
+}

src/BBT.StructureTools/Extension/ValidatedNotNullAttribute.cs

@@ -0,0 +1,12 @@
+namespace BBT.StructureTools.Extension
+{
+    using System;
+
+    /// <summary>
+    /// Indicates to code analysis that a method validates a particular parameter.
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Parameter)]
+    internal sealed class ValidatedNotNullAttribute : Attribute
+    {
+    }
+}