Fix bug in Yaml Extensions

Was caused by using a dedicated PhysicalFileProvider for rooted file paths.

Author: andrewlock

src/NetEscapades.Configuration.Yaml/YamlConfigurationExtensions.cs

@@ -72,21 +72,24 @@ public static IConfigurationBuilder AddYamlFile(this IConfigurationBuilder build
             {
                 throw new ArgumentException(Resources.FormatError_InvalidFilePath(), nameof(path));
             }
-
-            if (provider == null && Path.IsPathRooted(path))
-            {
-                provider = new PhysicalFileProvider(Path.GetDirectoryName(path));
-                path = Path.GetFileName(path);
-            }
-            var source = new YamlConfigurationSource
+            
+            return builder.AddYamlFile(s =>
             {
-                FileProvider = provider,
-                Path = path,
-                Optional = optional,
-                ReloadOnChange = reloadOnChange
-            };
-            builder.Add(source);
-            return builder;
+                s.FileProvider = provider;
+                s.Path = path;
+                s.Optional = optional;
+                s.ReloadOnChange = reloadOnChange;
+                s.ResolveFileProvider();
+            });
         }
+        
+        /// <summary>
+        /// Adds a YAML configuration source to <paramref name="builder"/>.
+        /// </summary>
+        /// <param name="builder">The <see cref="IConfigurationBuilder"/> to add to.</param>
+        /// <param name="configureSource">Configures the source.</param>
+        /// <returns>The <see cref="IConfigurationBuilder"/>.</returns>
+        public static IConfigurationBuilder AddYamlFile(this IConfigurationBuilder builder, Action<YamlConfigurationSource> configureSource)
+            => builder.Add(configureSource);
     }
 }

src/NetEscapades.Configuration.Yaml/YamlConfigurationSource.cs

@@ -9,7 +9,7 @@ public class YamlConfigurationSource : FileConfigurationSource
     {
         public override IConfigurationProvider Build(IConfigurationBuilder builder)
         {
-            FileProvider = FileProvider ?? builder.GetFileProvider();
+            EnsureDefaults(builder);
             return new YamlConfigurationProvider(this);
         }
     }

test/NetEscapades.Configuration.Yaml.Tests/YamlConfigurationExtensionsTests.cs

@@ -4,6 +4,7 @@
 using System;
 using System.IO;
 using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.FileProviders;
 using NetEscapades.Configuration.Yaml;
 using Xunit;
 
@@ -26,7 +27,7 @@ public void AddYamlFile_ThrowsIfFilePathIsNullOrEmpty(string path)
         }
 
         [Fact]
-        public void AddYamlFile_ThrowsIfFileDoesNotExistAtPath()
+        public void AddYamlFile_ThrowsIfFileDoesNotExistAtPathAndIsOptional()
         {
             // Arrange
             var path = "file-does-not-exist.Yaml";
@@ -35,5 +36,27 @@ public void AddYamlFile_ThrowsIfFileDoesNotExistAtPath()
             var ex = Assert.Throws<FileNotFoundException>(() => new ConfigurationBuilder().AddYamlFile(path).Build());
             Assert.StartsWith($"The configuration file '{path}' was not found and is not optional.", ex.Message);
         }
+        
+        [Fact]
+        public void AddYamlFile_DoesNotThrowIfFileDoesNotExistAndIsOptional()
+        {
+            // Arrange
+            var path = "file-does-not-exist.Yaml";
+
+            // Act and Assert
+            new ConfigurationBuilder().AddYamlFile(path, optional: true).Build();
+        }
+        
+        [Fact]
+        public void AddYamlFile_DoesNotThrowIfAbsolutePathDirectoryDoesNotExist()
+        {
+            // Arrange
+            var path = Path.Combine(Directory.GetCurrentDirectory(), "does", "not", "exist", "file-does-not-exist.Yaml");
+            
+            // Act and Assert
+            new ConfigurationBuilder()
+                .AddYamlFile(path, optional: true)
+                .Build();
+        }
     }
 }