add default HOCON loading methods (#151) (#152)

* working on adding default HOCON loading methods (#151)

Added ConfigurationFactory.FromFile method
Added new HOCON loading order per 151
Made ConfigurationFactory.Load Obsolete

* added specs

* cleaned up Default() method

* added default HOCON reading instructions to README

Author: Aaronontheweb

README.md

@@ -41,6 +41,13 @@ HOCON is significantly harder to specify and to parse than
 JSON. Think of it as moving the work from the person maintaining
 the config file to the computer program.
 
+## Default HOCON Configuration Sources
+By default the HOCON library will look for HOCON configurations in the following locations whenever you call the `Hocon.Configuration.ConfigurationFactory.Default()` method:
+
+1. [.NET Core / .NET Framework] An "app.conf" or an "app.hocon" file in the current working directory of the executable when it loads;
+2. [.NET Framework] - the `<hocon>` `ConfigurationSection` inside `App.config` or `Web.config`, which should also resolve #8 and #9 
+3. [.NET Framework] - and a legacy option, to load the old `<akka>` HOCON section for backwards compatibility purposes with all users who have been using HOCON with Akka.NET.
+
 ## Definitions
 
  - a _key_ is a string JSON would have to the left of `:` and a _value_ is

src/Hocon.Configuration.Test/ConfigurationSpec.cs

@@ -42,6 +42,18 @@ public void DeserializesHoconConfigurationFromNetConfigFile()
         }
 #endif
 
+        /// <summary>
+        /// Should follow the load order rules specified in https://github.com/akkadotnet/HOCON/issues/151
+        /// </summary>
+        [Fact]
+        public void CanLoadDefaultConfig()
+        {
+            var defaultConf = ConfigurationFactory.Default();
+            defaultConf.Should().NotBe(ConfigurationFactory.Empty);
+            defaultConf.HasPath("root.simple-string").Should().BeTrue();
+            defaultConf.GetString("root.simple-string").Should().Be("Hello HOCON2");
+        }
+
         [Fact]
         public void CanMergeObjects()
         {

src/Hocon.Configuration.Test/Hocon.Configuration.Tests.csproj

@@ -27,6 +27,12 @@
     <Reference Include="System.Configuration" />
   </ItemGroup>
 
+  <ItemGroup>
+    <None Update="app.conf">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
+  </ItemGroup>
+
   <Target Name="CopyCustomContent" AfterTargets="AfterBuild">
     <Copy SourceFiles="App.config" DestinationFiles="$(OutDir)\testhost.dll.config" />
   </Target>

src/Hocon.Configuration.Test/app.conf

@@ -0,0 +1,4 @@
+ root 
+{
+	simple-string = "Hello HOCON2"  
+}

src/Hocon.Configuration/ConfigurationFactory.cs

@@ -9,6 +9,7 @@
 using System.Configuration;
 using System.Diagnostics;
 using System.IO;
+using System.Linq;
 using System.Reflection;
 
 namespace Hocon
@@ -57,6 +58,7 @@ public static Config ParseString(string hocon)
         /// The configuration defined in the configuration file. If the section
         /// "akka" is not found, this returns an empty Config.
         /// </returns>
+        [Obsolete("Call the ConfigurationFactory.Default method instead.")]
         public static Config Load()
         {
            return Load("akka");
@@ -78,14 +80,54 @@ public static Config Load(string sectionName)
 
            return config;
         }
+
+        /// <summary>
+        /// Parses a HOCON file from the filesystem.
+        /// </summary>
+        /// <param name="filePath">The path to the file.</param>
+        /// <returns>A parsed HOCON configuration object.</returns>
+        /// <throws>ConfigurationException, when the supplied filePath can't be found.</throws>
+        public static Config FromFile(string filePath)
+        {
+            if (File.Exists(filePath))
+            {
+                return ParseString(File.ReadAllText(filePath));
+            }
+
+            throw new ConfigurationException($"No HOCON file at {filePath} could be found.");
+        }
+
+        public static readonly string[] DefaultHoconFilePaths = { "app.conf", "app.hocon" };
+
         /// <summary>
         /// Retrieves the default configuration that Akka.NET uses
         /// when no configuration has been defined.
         /// </summary>
         /// <returns>The configuration that contains default values for all options.</returns>
         public static Config Default()
         {
-            return FromResource("Default.conf");
+            // attempt to load .hocon files first
+            foreach (var path in DefaultHoconFilePaths.Where(x => File.Exists(x)))
+            {
+                return FromFile(path);
+            }
+
+            // if we made it this far: no default HOCON files found. Check app.config
+            try
+            {
+                var def = Load("hocon"); // new default
+                if (def == null || def.IsEmpty)
+                {
+                    return Load("akka"); // old Akka.NET-specific default
+                }
+
+            }
+            catch
+            {
+
+            }
+
+            return Empty;
         }
 
         /// <summary>