Implement support for versioned prompt files

DotPrompt.Tests/DotPrompt.Tests.csproj

@@ -10,9 +10,9 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.13.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
     <PackageReference Include="xunit" Version="2.9.3" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="3.0.2">
+    <PackageReference Include="xunit.runner.visualstudio" Version="3.1.4">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>
@@ -35,6 +35,9 @@
     <None Update="duplicate-name-prompts\*">
       <CopyToOutputDirectory>Always</CopyToOutputDirectory>
     </None>
+    <None Update="multiple-version-prompts\*">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
   </ItemGroup>
 
   <ItemGroup>

DotPrompt.Tests/Extensions/OpenAi/OpenAiExtensionsTests.cs

@@ -1,3 +1,4 @@
+using System.Reflection;
 using DotPrompt.Extensions.OpenAi;
 using OpenAI.Chat;
 
@@ -105,13 +106,10 @@ public void ToOpenAiChatCompletionOptions_WithJsonSchemaFormat_ReturnsAValidOpti
 
         const string expectedSchema = """{"type":"object","required":["field1"],"properties":{"field1":{"type":"string","description":"An example description for the field"},"field2":{"type":"array","items":{"type":"string"}}},"additionalProperties":false}""";
 
-        var jsonSchemaProperty = options.ResponseFormat.GetType().GetProperty("JsonSchema");
-        var jsonSchemaValue = jsonSchemaProperty!.GetValue(options.ResponseFormat);
+        var jsonSchemaValue = GetInternalProperty<object>(options.ResponseFormat, "JsonSchema");
+        var schemaValue = GetInternalProperty<BinaryData>(jsonSchemaValue, "Schema");
 
-        var schemaProperty = jsonSchemaValue!.GetType().GetProperty("Schema");
-        var schemaValue = schemaProperty!.GetValue(jsonSchemaValue) as BinaryData;
-
-        var optionsSchema = schemaValue!.ToString();
+        var optionsSchema = schemaValue.ToString();
 
         Assert.Equal(expectedSchema, optionsSchema);
 
@@ -159,4 +157,24 @@ public void ToOpenAiChatCompletionOptions_WithInvalidFormat_ThrowsAnException()
         var exception = Assert.Throws<DotPromptException>(() => promptFileMock.ToOpenAiChatCompletionOptions());
         Assert.Contains("The requested output format is not available", exception.Message);
     }
+
+    private static T GetInternalProperty<T>(object obj, string propertyName)
+    {
+        var property = obj.GetType().GetProperty(propertyName, 
+            BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance);
+
+        if (property == null)
+        {
+            throw new InvalidOperationException($"Property '{propertyName}' not found on type '{obj.GetType().Name}'");
+        }
+
+        var value = property.GetValue(obj);
+
+        if (value is T result)
+        {
+            return result;
+        }
+
+        throw new InvalidOperationException($"Property '{propertyName}' is not of expected type '{typeof(T).Name}'");
+    }
 }

DotPrompt.Tests/PromptFileTests.cs

@@ -21,6 +21,7 @@ public void FromFile_BasicPrompt_ProducesValidPromptFile()
         };
 
         Assert.Equal("basic", promptFile.Name);
+        Assert.Equal(1, promptFile.Version);
 
         Assert.NotNull(promptFile.Model);
         Assert.Equal("claude-3-5-sonnet-latest", promptFile.Model);
@@ -213,6 +214,30 @@ public void FromStream_WithMissingModelName_IsPersistedAsNullValue()
         Assert.Null(promptFile.Model);
     }
 
+    [Theory]
+    [InlineData(int.MinValue, true)]
+    [InlineData(-1, true)]
+    [InlineData(0, false)]
+    [InlineData(1, false)]
+    public void FromStream_WithInvalidVersion_ThrowsAnException(int version, bool throwsException)
+    {
+        var content = $"name: test\nversion: {version}\nprompts:\n  system: System prompt\n  user: User prompt";
+        using var ms = new MemoryStream(Encoding.UTF8.GetBytes(content));
+        ms.Seek(0, SeekOrigin.Begin);
+
+        var act = () => PromptFile.FromStream("test", ms);
+
+        if (throwsException)
+        {
+            var exception = Assert.Throws<DotPromptException>(act);
+            Assert.Contains("The version of the prompt file cannot be negative", exception.Message);
+        }
+        else
+        {
+            act();
+        }
+    }
+
     [Fact]
     public void GenerateUserPrompt_UsingDefaults_CorrectlyGeneratesPromptFromTemplate()
     {
@@ -368,7 +393,7 @@ public void ToStream_WithValidInput_ProducesExpectedContent()
             }
         };
 
-        var expected = "name: test\nconfig:\n  input:\n    parameters:\n      test?: string\n  outputFormat: Json\n  maxTokens: 500\nprompts:\n  system: system prompt\n  user: user prompt\n";
+        const string expected = "name: test\nversion: 1\nconfig:\n  input:\n    parameters:\n      test?: string\n  outputFormat: Json\n  maxTokens: 500\nprompts:\n  system: system prompt\n  user: user prompt\n";
 
         var ms = new MemoryStream();
         promptFile.ToStream(ms);

DotPrompt.Tests/PromptManagerTests.cs

@@ -41,6 +41,21 @@ public void PromptManager_WithPathSpecified_LoadsPromptsFromSpecifiedLocation()
         Assert.Contains("basic", actualPrompts);
         Assert.Contains("example-with-name", actualPrompts);
     }
+
+    [Fact]
+    public void PromptManager_ListPromptFileNamesWithVersions_ReturnsListOfPromptFileNamesAndVersions()
+    {
+        var manager = new PromptManager();
+
+        var expectedPrompts = new List<string> { "basic:1", "example-with-name:1" };
+        var actualPrompts = manager.ListPromptFileNamesWithVersions().ToList();
+
+        Assert.Equal(expectedPrompts.Count, actualPrompts.Count);
+        foreach (var expectedPrompt in expectedPrompts)
+        {
+            Assert.Contains(expectedPrompt, actualPrompts);
+        }
+    }
 
     [Fact]
     public void PromptManager_WithDuplicateNames_ThrowsException()
@@ -53,6 +68,54 @@ public void PromptManager_WithDuplicateNames_ThrowsException()
         Assert.Contains("a duplicate exists", exception.Message);
     }
 
+    [Fact]
+    public void PromptManager_WithDifferentVersions_LoadsSuccessfully()
+    {
+        var manager = new PromptManager("multiple-version-prompts");
+
+        var expectedPrompts = new List<string> { "basic:1", "basic:2" };
+        var actualPrompts = manager.ListPromptFileNamesWithVersions().ToList();
+
+        Assert.Equal(expectedPrompts.Count, actualPrompts.Count);
+        foreach (var expectedPrompt in expectedPrompts)
+        {
+            Assert.Contains(expectedPrompt, actualPrompts);
+        }
+    }
+
+    [Fact]
+    public void PromptManager_WhenRequestedByName_ReturnsLatestVersion()
+    {
+        var manager = new PromptManager("multiple-version-prompts");
+
+        var expectedPrompt = PromptFile.FromFile("multiple-version-prompts/basic-new.prompt");
+        var actualPrompt = manager.GetPromptFile("basic");
+
+        Assert.Equivalent(expectedPrompt, actualPrompt, strict: true);
+    }
+
+    [Fact]
+    public void PromptManager_WhenRequestedByNameAndVersion_ReturnsCorrectVersion()
+    {
+        var manager = new PromptManager("multiple-version-prompts");
+
+        var expectedPrompt = PromptFile.FromFile("multiple-version-prompts/basic.prompt");
+        var actualPrompt = manager.GetPromptFile("basic", 1);
+
+        Assert.Equivalent(expectedPrompt, actualPrompt, strict: true);
+    }
+
+    [Fact]
+    public void PromptManager_WhenRequestedByNameAndInvalidVersion_ThrowsException()
+    {
+        var manager = new PromptManager("multiple-version-prompts");
+
+        var act = () => manager.GetPromptFile("basic", 3);
+
+        var exception = Assert.Throws<DotPromptException>(act);
+        Assert.Equal("No prompt file with that name and version has been loaded", exception.Message);   
+    }
+
     [Fact]
     public void GetPromptFile_WhenRequestedWithValidName_LoadsExpectedPromptFile()
     {

DotPrompt.Tests/multiple-version-prompts/basic-new.prompt

@@ -0,0 +1,20 @@
+name: basic
+version: 2
+config:
+  outputFormat: text
+  temperature: 0.9
+  maxTokens: 500
+  input:
+    parameters:
+      country: string
+      style?: string
+    default:
+      country: Malta
+prompts:
+  system: |
+    You are a helpful AI assistant that enjoys making capybara related puns. You should work as many into your response as possible
+  user: |
+    I am looking at going on holiday to {{ country }} and would like to know more about it, what can you tell me?
+    {% if style -%}
+    Can you answer in the style of a {{ style }}
+    {% endif -%}

DotPrompt.Tests/multiple-version-prompts/basic.prompt

@@ -0,0 +1,20 @@
+name: basic
+version: 1
+config:
+  outputFormat: text
+  temperature: 0.9
+  maxTokens: 500
+  input:
+    parameters:
+      country: string
+      style?: string
+    default:
+      country: Malta
+prompts:
+  system: |
+    You are a helpful AI assistant that enjoys making penguin related puns. You should work as many into your response as possible
+  user: |
+    I am looking at going on holiday to {{ country }} and would like to know more about it, what can you tell me?
+    {% if style -%}
+    Can you answer in the style of a {{ style }}
+    {% endif -%}

DotPrompt/DotPrompt.csproj

@@ -21,9 +21,9 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Fluid.Core" Version="2.23.0" />
-    <PackageReference Include="JsonSchema.Net" Version="7.3.4" />
-    <PackageReference Include="OpenAI" Version="2.1.0" />
+    <PackageReference Include="Fluid.Core" Version="2.25.0" />
+    <PackageReference Include="JsonSchema.Net" Version="7.4.0" />
+    <PackageReference Include="OpenAI" Version="2.3.0" />
     <PackageReference Include="YamlDotNet" Version="16.3.0" />
   </ItemGroup>
 

DotPrompt/PromptFile.cs

@@ -23,6 +23,11 @@ public partial class PromptFile
     /// </summary>
     public required string Name { get; set; }
 
+    /// <summary>
+    /// Gets, sets the version of the prompt file.
+    /// </summary>
+    public int Version { get; set; } = 1;
+
     /// <summary>
     /// Gets, sets the name of the model (or deployment) the prompt should be executed using
     /// </summary>
@@ -113,6 +118,12 @@ public static PromptFile FromStream(string name, Stream inputStream)
         {
             promptFile.Name = name;
         }
+
+        // If the prompt version is negative, then throw an exception
+        if (promptFile.Version < 0)
+        {
+            throw new DotPromptException("The version of the prompt file cannot be negative");
+        }
 
         // If the prompt output configuration is null then create a new one and set the output format. This is to handle
         // instances where the output format is slightly older and is set at the top level

DotPrompt/PromptManager.cs

@@ -2,12 +2,19 @@
 
 namespace DotPrompt;
 
+/// <summary>
+/// Identifies a .prompt file uniquely using its name and version
+/// </summary>
+/// <param name="Name">The name of the prompt file</param>
+/// <param name="Version">The prompt file version</param>
+public record PromptFileIdentifier(string Name, int Version);
+
 /// <summary>
 /// Manages loading and accessing of .prompt files from a specified directory.
 /// </summary>
 public class PromptManager : IPromptManager
 {
-    private readonly ConcurrentDictionary<string, PromptFile> _promptFiles = new();
+    private readonly ConcurrentDictionary<PromptFileIdentifier, PromptFile> _promptFiles = new();
 
     /// <summary>
     /// Creates a new instance of the <see cref="PromptManager"/> using a default instance of the
@@ -30,35 +37,67 @@ public PromptManager(IPromptStore promptStore)
     {
         foreach (var promptFile in promptStore.Load())
         {
-            if (!_promptFiles.TryAdd(promptFile.Name, promptFile))
+            if (!_promptFiles.TryAdd(new PromptFileIdentifier(promptFile.Name, promptFile.Version), promptFile))
             {
-                throw new DotPromptException($"Unable to add prompt file with name '{promptFile.Name}' as a duplicate exists");
+                throw new DotPromptException($"Unable to add prompt file with name '{promptFile.Name}' and version {promptFile.Version} as a duplicate exists");
             }
         }
     }
 
     /// <summary>
-    /// Retrieves a <see cref="PromptFile"/> by its name
+    /// Retrieves a <see cref="PromptFile"/> by its name. If multiple versions of the prompt file are found, the
+    /// latest version is returned.
     /// </summary>
     /// <param name="name">The name of the prompt file to retrieve</param>
     /// <returns>The <see cref="PromptFile"/> with the specified name</returns>
     /// <exception cref="DotPromptException">Thrown when no prompt file with the specified name is found</exception>
     public PromptFile GetPromptFile(string name)
     {
-        if (_promptFiles.TryGetValue(name, out var promptFile)) 
-        {
-            return promptFile;
-        }
+        var promptFilesWithName = _promptFiles
+            .Where(kvp => kvp.Key.Name == name)
+            .OrderByDescending(kvp => kvp.Key.Version)
+            .ToList();
 
-        throw new DotPromptException("No prompt file with that name has been loaded");
+        return promptFilesWithName.Count == 0
+            ? throw new DotPromptException("No prompt file with that name has been loaded")
+            : promptFilesWithName[0].Value;
     }
 
+    /// <summary>
+    /// Retrieves a <see cref="PromptFile"/> by its name and version.
+    /// </summary>
+    /// <param name="name">The name of the prompt file to retrieve</param>
+    /// <param name="version">The version of the prompt file to retrieve</param>
+    /// <returns>The <see cref="PromptFile"/> with the specified name and version</returns>
+    /// <exception cref="DotPromptException">Thrown when no prompt file with the specified name and version is found</exception>
+    public PromptFile GetPromptFile(string name, int version)
+    {
+        return _promptFiles.TryGetValue(new PromptFileIdentifier(name, version), out var promptFile)
+            ? promptFile
+            : throw new DotPromptException("No prompt file with that name and version has been loaded");
+    }
+
     /// <summary>
     /// Lists the names of all loaded prompt files.
     /// </summary>
     /// <returns>An enumerable collection of prompt file names.</returns>
     public IEnumerable<string> ListPromptFileNames()
     {
-        return _promptFiles.Keys.Select(k => k);
+        return _promptFiles
+            .DistinctBy(kvp => kvp.Key.Name)
+            .OrderBy(kvp => kvp.Key.Name)
+            .Select(kvp => $"{kvp.Key.Name}");
+    }
+
+    /// <summary>
+    /// Lists the names of all loaded prompts with their versions.
+    /// </summary>
+    /// <returns>An enumerable collection of prompt file names and versions.</returns>
+    public IEnumerable<string> ListPromptFileNamesWithVersions()
+    {
+        return _promptFiles
+            .OrderBy(kvp => kvp.Key.Name)
+            .ThenByDescending(kvp => kvp.Key.Version)
+            .Select(kvp => $"{kvp.Key.Name}:{kvp.Key.Version}");
     }
 }