Added exception handling to make any missing config settings really obvious

Author: robdmoore

AzureWebFarm.OctopusDeploy.Tests/AzureWebFarm.OctopusDeploy.Tests.csproj

@@ -91,6 +91,7 @@
   </ItemGroup>
   <ItemGroup>
     <Compile Include="Infrastructure\AzureEnvironmentTests.cs" />
+    <Compile Include="Infrastructure\ConfigSettingsTests.cs" />
     <Compile Include="Infrastructure\OctopusDeployTests.cs" />
     <Compile Include="Infrastructure\RegistryEditorTests.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />

AzureWebFarm.OctopusDeploy.Tests/Infrastructure/ConfigSettingsTests.cs

@@ -0,0 +1,22 @@
+using System;
+using AzureWebFarm.OctopusDeploy.Infrastructure;
+using Shouldly;
+using Xunit;
+
+namespace AzureWebFarm.OctopusDeploy.Tests.Infrastructure
+{
+    public class ConfigSettingsTests
+    {
+        [Fact]
+        public void GivenExceptionWhenGettingConfigSetting_WhenConstructingConfigSettings_ThenThrowNiceException()
+        {
+            var e = new Exception("Error");
+            Func<string, string> getter = _ => { throw e; };
+
+            var ex = Assert.Throws<UnableToGetConfigSettingException>(() => new ConfigSettings(getter, getter));
+
+            ex.Message.ShouldBe("Unable to get config setting: OctopusServer");
+            ex.InnerException.ShouldBe(e);
+        }
+    }
+}

AzureWebFarm.OctopusDeploy/Infrastructure/ConfigSettings.cs

@@ -35,14 +35,14 @@ internal class ConfigSettings : IConfigSettings
 
         public ConfigSettings(Func<string, string> configSettingsGetter, Func<string, string> configPathGetter)
         {
-            _octopusServer = configSettingsGetter(OctopusServerConfigName);
-            _octopusApiKey = configSettingsGetter(OctopusApiKeyConfigName);
-            _tentacleEnvironment = configSettingsGetter(TentacleEnvironmentConfigName);
-            _tentacleRole = configSettingsGetter(TentacleRoleConfigName);
-            _tentacleMachineNameSuffix = configSettingsGetter(TentacleMachineNameSuffixConfigName);
-
-            _tentacleDeploymentsPath = configPathGetter(TentacleDeploymentsPathConfigName);
-            _tentacleInstallPath = configPathGetter(TentacleInstallPathConfigName);
+            _octopusServer = SafeGetConfigSetting(configSettingsGetter, OctopusServerConfigName);
+            _octopusApiKey = SafeGetConfigSetting(configSettingsGetter, OctopusApiKeyConfigName);
+            _tentacleEnvironment = SafeGetConfigSetting(configSettingsGetter, TentacleEnvironmentConfigName);
+            _tentacleRole = SafeGetConfigSetting(configSettingsGetter, TentacleRoleConfigName);
+            _tentacleMachineNameSuffix = SafeGetConfigSetting(configSettingsGetter, TentacleMachineNameSuffixConfigName);
+
+            _tentacleDeploymentsPath = SafeGetConfigSetting(configPathGetter, TentacleDeploymentsPathConfigName);
+            _tentacleInstallPath = SafeGetConfigSetting(configPathGetter, TentacleInstallPathConfigName);
         }
 
         public string OctopusServer { get { return _octopusServer; } }
@@ -58,5 +58,31 @@ public bool IsConfigSettingName(string name)
         {
             return ConfigSettingsNames.Contains(name);
         }
+
+        public string SafeGetConfigSetting(Func<string, string> configSettingsGetter, string settingName)
+        {
+            try
+            {
+                return configSettingsGetter(settingName) ?? "";
+            }
+            catch (Exception e)
+            {
+                throw new UnableToGetConfigSettingException(settingName, e);
+            }
+        }
+    }
+
+    /// <summary>
+    /// Error getting a config setting.
+    /// </summary>
+    public class UnableToGetConfigSettingException : Exception
+    {
+        /// <summary>
+        /// Create the exception for the setting in question.
+        /// </summary>
+        /// <param name="settingName">The name of the setting an error was raised for</param>
+        /// <param name="exception">The exception that was raised when getting the setting</param>
+        public UnableToGetConfigSettingException(string settingName, Exception exception)
+            : base("Unable to get config setting: " + settingName, exception) {}
     }
 }