Merge pull request #1 from laurensb/check

Fixed precondition checks

.gitignore

@@ -3,3 +3,4 @@ HttpServer.Sample/bin
 HttpServer.Test/bin
 HttpServer/bin
 Tutorial/bin
+HttpServer_Test/bin

HttpServer.sln

@@ -3,6 +3,8 @@ Microsoft Visual Studio Solution File, Format Version 11.00
 # Visual C# Express 2010
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "HttpServer", "HttpServer\HttpServer.csproj", "{455E7D70-1C85-4D7F-9F01-DC801B8B8C34}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "HttpServer_Test", "HttpServer_Test\HttpServer_Test.csproj", "{C3CC0769-9814-4896-8599-9EB0B807E785}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -16,6 +18,12 @@ Global
 		{455E7D70-1C85-4D7F-9F01-DC801B8B8C34}.Release|Any CPU.Build.0 = Release|Any CPU
 		{455E7D70-1C85-4D7F-9F01-DC801B8B8C34}.Test|Any CPU.ActiveCfg = Test|Any CPU
 		{455E7D70-1C85-4D7F-9F01-DC801B8B8C34}.Test|Any CPU.Build.0 = Test|Any CPU
+		{C3CC0769-9814-4896-8599-9EB0B807E785}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{C3CC0769-9814-4896-8599-9EB0B807E785}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{C3CC0769-9814-4896-8599-9EB0B807E785}.Release|Any CPU.Build.0 = Release|Any CPU
+		{C3CC0769-9814-4896-8599-9EB0B807E785}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{C3CC0769-9814-4896-8599-9EB0B807E785}.Test|Any CPU.Build.0 = Debug|Any CPU
+		{C3CC0769-9814-4896-8599-9EB0B807E785}.Test|Any CPU.ActiveCfg = Debug|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE

HttpServer/Check.cs

@@ -3,61 +3,71 @@
 namespace HttpServer
 {
 	/// <summary>
-	/// Small design by contract implementation.
+	/// Utility class for precondition checks.
 	/// </summary>
 	public static class Check
 	{
 		/// <summary>
-		/// Check whether a parameter is empty.
+		/// Check whether a parameter is non empty.
 		/// </summary>
 		/// <param name="value">Parameter value</param>
 		/// <param name="parameterOrErrorMessage">Parameter name, or error description.</param>
 		/// <exception cref="ArgumentException">value is empty.</exception>
-		public static void NotEmpty(string value, string parameterOrErrorMessage)
+        public static void NotEmpty(string value, string parameterOrErrorMessage)
 		{
+            if (string.IsNullOrEmpty(parameterOrErrorMessage))
+                Check.NotEmpty(parameterOrErrorMessage, "parameterOrErrorMessage");
+
 			if (!string.IsNullOrEmpty(value))
 				return;
 
-			if (parameterOrErrorMessage.IndexOf(' ') == -1)
-				throw new ArgumentException("'" + parameterOrErrorMessage + "' cannot be empty.", parameterOrErrorMessage);
-
-			throw new ArgumentException(parameterOrErrorMessage);
+            bool isParameterName = parameterOrErrorMessage.IndexOf(' ') == -1;
+			if (isParameterName)
+                throw new ArgumentException(String.Format("'{0}' cannot be empty.", parameterOrErrorMessage), parameterOrErrorMessage);
+            else
+                throw new ArgumentException(parameterOrErrorMessage);
 		}
 
 		/// <summary>
-		/// Checks whether a parameter is null.
+		/// Checks whether a parameter is non null.
 		/// </summary>
 		/// <param name="value">Parameter value</param>
 		/// <param name="parameterOrErrorMessage">Parameter name, or error description.</param>
 		/// <exception cref="ArgumentNullException">value is null.</exception>
 		public static void Require(object value, string parameterOrErrorMessage)
 		{
+            Check.NotEmpty(parameterOrErrorMessage, "parameterOrErrorMessage");
+
 			if (value != null)
 				return;
 
-			if (parameterOrErrorMessage.IndexOf(' ') == -1)
-				throw new ArgumentNullException("'" + parameterOrErrorMessage + "' cannot be null.", parameterOrErrorMessage);
-
-			throw new ArgumentNullException(parameterOrErrorMessage);
+            bool isParameterName = parameterOrErrorMessage.IndexOf(' ') == -1;
+            if (isParameterName)
+                throw new ArgumentNullException(parameterOrErrorMessage, String.Format("'{0}' cannot be null.", parameterOrErrorMessage));
+            else
+			    throw new ArgumentNullException(null, parameterOrErrorMessage);
 
 		}
 
 		/// <summary>
-		/// Checks whether a parameter is null.
+		/// Checks whether an integer parameter is at least a certain value.
 		/// </summary>
-		/// <param name="minValue"></param>
+		/// <param name="minValue">Minimum value</param>
 		/// <param name="value">Parameter value</param>
 		/// <param name="parameterOrErrorMessage">Parameter name, or error description.</param>
-		/// <exception cref="ArgumentException">value is null.</exception>
-		public static void Min(int minValue, object value, string parameterOrErrorMessage)
+		/// <exception cref="ArgumentException">value is smaller than minValue.</exception>
+		public static void Min(int minValue, int value, string parameterOrErrorMessage)
 		{
-			if (value != null)
-				return;
+            Check.NotEmpty(parameterOrErrorMessage, "parameterOrErrorMessage");
 
-			if (parameterOrErrorMessage.IndexOf(' ') == -1)
-				throw new ArgumentException("'" + parameterOrErrorMessage + "' must be at least " + minValue + ".", parameterOrErrorMessage);
+            if (minValue <= value)
+				return;
 
-			throw new ArgumentException(parameterOrErrorMessage);
+            bool isParameterName = parameterOrErrorMessage.IndexOf(' ') == -1;
+            if (isParameterName)
+				throw new ArgumentException(String.Format("'{0}' must be at least {1}.", parameterOrErrorMessage, minValue));
+            else
+			    throw new ArgumentException(parameterOrErrorMessage);
 
 		}
 	}

HttpServer_Test/CheckTests.cs

@@ -0,0 +1,56 @@
+using System;
+using HttpServer;
+using NUnit.Framework;
+
+namespace HttpServer_Test
+{
+	[TestFixture]
+	public class CheckTests
+	{
+		[Test]
+		public void TestNotEmpty()
+		{
+            Check.NotEmpty("string", "error");
+            Check.NotEmpty("another string", "another error");
+
+            // Even though the argument to check is non empty an exception is expected,
+            // if this was not the case the missing error message would only be discovered when the check fails (possibly in production)
+            Assert.That(() => Check.NotEmpty("something not empty", null), Throws.TypeOf<ArgumentException>());
+
+            Assert.That(() => Check.NotEmpty("", "error"), Throws.TypeOf<ArgumentException>());
+            Assert.That(() => Check.NotEmpty("", "bad parameter"), Throws.TypeOf<ArgumentException>());
+            Assert.That(() => Check.NotEmpty("", null), Throws.TypeOf<ArgumentException>());
+
+            Assert.That(() => Check.NotEmpty(null, "null"), Throws.TypeOf<ArgumentException>());
+            Assert.That(() => Check.NotEmpty(null, "cannot be null"), Throws.TypeOf<ArgumentException>());
+            Assert.That(() => Check.NotEmpty(null, null), Throws.TypeOf<ArgumentException>());
+        }
+
+        [Test]
+        public void testRequire()
+        {
+            Object someObject = "some string";
+
+            Check.Require(someObject, "parameter");
+            Check.Require(someObject, "error message");
+            Assert.That(() => Check.Require(someObject, null), Throws.TypeOf<ArgumentException>());
+
+            Assert.That(() => Check.Require(null, "null"), Throws.TypeOf<ArgumentNullException>());
+            Assert.That(() => Check.Require(null, "cannot be null"), Throws.TypeOf<ArgumentNullException>());
+            Assert.That(() => Check.Require(null, null), Throws.TypeOf<ArgumentException>());
+        }
+
+        [Test]
+        public void TestMin()
+        {
+            Check.Min(0, 100, "value");
+            Check.Min(-100, 0, "value");
+            Check.Min(int.MaxValue, int.MaxValue, "value");
+            Assert.That(() => Check.Min(0, 100, null), Throws.TypeOf<ArgumentException>());
+
+            Assert.That(() => Check.Min(100, 0, "value"), Throws.TypeOf<ArgumentException>());
+            Assert.That(() => Check.Min(0, -100, "value"), Throws.TypeOf<ArgumentException>());
+            Assert.That(() => Check.Min(int.MaxValue, int.MinValue, "value"), Throws.TypeOf<ArgumentException>());
+        }
+	}
+}

HttpServer_Test/HttpServer_Test.csproj

@@ -0,0 +1,57 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003" DefaultTargets="Build">
+  <PropertyGroup>
+    <ProjectGuid>{C3CC0769-9814-4896-8599-9EB0B807E785}</ProjectGuid>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
+    <OutputType>Library</OutputType>
+    <RootNamespace>HttpServer_Test</RootNamespace>
+    <AssemblyName>HttpServer_Test</AssemblyName>
+    <TargetFrameworkVersion>v4.0</TargetFrameworkVersion>
+    <TargetFrameworkProfile>Client</TargetFrameworkProfile>
+    <AppDesignerFolder>Properties</AppDesignerFolder>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Platform)' == 'AnyCPU' ">
+    <PlatformTarget>x86</PlatformTarget>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)' == 'Debug' ">
+    <OutputPath>bin\Debug\</OutputPath>
+    <DebugSymbols>True</DebugSymbols>
+    <DebugType>Full</DebugType>
+    <Optimize>False</Optimize>
+    <CheckForOverflowUnderflow>True</CheckForOverflowUnderflow>
+    <DefineConstants>DEBUG;TRACE</DefineConstants>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)' == 'Release' ">
+    <OutputPath>bin\Release\</OutputPath>
+    <DebugSymbols>False</DebugSymbols>
+    <DebugType>None</DebugType>
+    <Optimize>True</Optimize>
+    <CheckForOverflowUnderflow>False</CheckForOverflowUnderflow>
+    <DefineConstants>TRACE</DefineConstants>
+  </PropertyGroup>
+  <ItemGroup>
+    <Reference Include="nunit.framework, Version=2.6.4.14350, Culture=neutral, PublicKeyToken=96d09a1eb7f44a77, processorArchitecture=MSIL">
+      <SpecificVersion>False</SpecificVersion>
+      <HintPath>..\packages\NUnit.2.6.4\lib\nunit.framework.dll</HintPath>
+    </Reference>
+    <Reference Include="System" />
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="Properties\AssemblyInfo.cs" />
+    <Compile Include="CheckTests.cs" />
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\HttpServer\HttpServer.csproj">
+      <Project>{455E7D70-1C85-4D7F-9F01-DC801B8B8C34}</Project>
+      <Name>HttpServer</Name>
+    </ProjectReference>
+  </ItemGroup>
+  <ItemGroup>
+    <Service Include="{82A7F48D-3B50-4B1E-B82E-3ADA8210C358}" />
+  </ItemGroup>
+  <ItemGroup>
+    <None Include="packages.config" />
+  </ItemGroup>
+  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
+</Project>

HttpServer_Test/Properties/AssemblyInfo.cs

@@ -0,0 +1,31 @@
+#region Using directives
+
+using System;
+using System.Reflection;
+using System.Runtime.InteropServices;
+
+#endregion
+
+// General Information about an assembly is controlled through the following 
+// set of attributes. Change these attribute values to modify the information
+// associated with an assembly.
+[assembly: AssemblyTitle("HttpServer_Test")]
+[assembly: AssemblyDescription("")]
+[assembly: AssemblyConfiguration("")]
+[assembly: AssemblyCompany("")]
+[assembly: AssemblyProduct("HttpServer_Test")]
+[assembly: AssemblyCopyright("Copyright 2015")]
+[assembly: AssemblyTrademark("")]
+[assembly: AssemblyCulture("")]
+
+// This sets the default COM visibility of types in the assembly to invisible.
+// If you need to expose a type to COM, use [ComVisible(true)] on that type.
+[assembly: ComVisible(false)]
+
+// The assembly version has following format :
+//
+// Major.Minor.Build.Revision
+//
+// You can specify all the values or you can use the default the Revision and 
+// Build Numbers by using the '*' as shown below:
+[assembly: AssemblyVersion("1.0.*")]

HttpServer_Test/packages.config

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<packages>
+  <package id="NUnit" version="2.6.4" targetFramework="net40-Client" />
+</packages>