feat: Implement include-fragment in compiler (#67)

Author: Mielek

src/Authoring/IBackendContext.cs

@@ -59,6 +59,13 @@ public interface IBackendContext : IHaveExpressionContext
     /// <param name="config"></param>
     void CacheStoreValue(CacheStoreValueConfig config);
 
+    /// <summary>
+    /// The policy inserts the policy fragment as-is at the location you select in the policy definition.<br />
+    /// Compiled to <a href="https://learn.microsoft.com/en-us/azure/api-management/include-fragment-policy">include-fragment</a> policy.
+    /// </summary>
+    /// <param name="fragmentId">A string. Specifies the identifier (name) of a policy fragment created in the API Management instance. Policy expressions aren't allowed.</param>
+    void IncludeFragment(string fragmentId);
+
     /// <summary>
     /// Inlines the specified policy as is to policy document.
     /// </summary>

src/Authoring/IInboundContext.cs

@@ -254,6 +254,13 @@ public interface IInboundContext : IHaveExpressionContext
     /// <param name="config"></param>
     void CacheRemoveValue(CacheRemoveValueConfig config);
 
+    /// <summary>
+    /// The policy inserts the policy fragment as-is at the location you select in the policy definition.<br />
+    /// Compiled to <a href="https://learn.microsoft.com/en-us/azure/api-management/include-fragment-policy">include-fragment</a> policy.
+    /// </summary>
+    /// <param name="fragmentId">A string. Specifies the identifier (name) of a policy fragment created in the API Management instance. Policy expressions aren't allowed.</param>
+    void IncludeFragment(string fragmentId);
+
     /// <summary>
     /// Inlines the specified policy as is to policy document.
     /// </summary>

src/Authoring/IOnErrorContext.cs

@@ -110,6 +110,13 @@ public interface IOnErrorContext : IHaveExpressionContext
     /// <param name="config"></param>
     void CacheStoreValue(CacheStoreValueConfig config);
 
+    /// <summary>
+    /// The policy inserts the policy fragment as-is at the location you select in the policy definition.<br />
+    /// Compiled to <a href="https://learn.microsoft.com/en-us/azure/api-management/include-fragment-policy">include-fragment</a> policy.
+    /// </summary>
+    /// <param name="fragmentId">A string. Specifies the identifier (name) of a policy fragment created in the API Management instance. Policy expressions aren't allowed.</param>
+    void IncludeFragment(string fragmentId);
+
     /// <summary>
     /// Inlines the specified policy as is to policy document.
     /// </summary>

src/Authoring/IOutboundContext.cs

@@ -132,6 +132,13 @@ public interface IOutboundContext : IHaveExpressionContext
     /// <param name="config"></param>
     void CacheStoreValue(CacheStoreValueConfig config);
 
+    /// <summary>
+    /// The policy inserts the policy fragment as-is at the location you select in the policy definition.<br />
+    /// Compiled to <a href="https://learn.microsoft.com/en-us/azure/api-management/include-fragment-policy">include-fragment</a> policy.
+    /// </summary>
+    /// <param name="fragmentId">A string. Specifies the identifier (name) of a policy fragment created in the API Management instance. Policy expressions aren't allowed.</param>
+    void IncludeFragment(string fragmentId);
+
     /// <summary>
     /// Inlines the specified policy as is to policy document.
     /// </summary>

src/Core/Compiling/Policy/IncludeFragmentCompiler.cs

@@ -0,0 +1,33 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using System.Xml.Linq;
+
+using Azure.ApiManagement.PolicyToolkit.Authoring;
+using Azure.ApiManagement.PolicyToolkit.Compiling.Diagnostics;
+
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+
+namespace Azure.ApiManagement.PolicyToolkit.Compiling.Policy;
+
+public class IncludeFragmentCompiler : IMethodPolicyHandler
+{
+    public string MethodName => nameof(IInboundContext.IncludeFragment);
+
+    public void Handle(ICompilationContext context, InvocationExpressionSyntax node)
+    {
+        if (node.ArgumentList.Arguments.Count != 1)
+        {
+            context.Report(Diagnostic.Create(
+                CompilationErrors.ArgumentCountMissMatchForPolicy,
+                node.ArgumentList.GetLocation(),
+                "include-fragment"
+            ));
+            return;
+        }
+
+        var fragmentId = node.ArgumentList.Arguments[0].Expression.ProcessParameter(context);
+        context.AddPolicy(new XElement("include-fragment", new XAttribute("fragment-id", fragmentId)));
+    }
+}

test/Test.Core/Compiling/IncludeFragmentTests.cs

@@ -0,0 +1,43 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+namespace Azure.ApiManagement.PolicyToolkit.Compiling;
+
+[TestClass]
+public class IncludeFragmentTests
+{
+    [TestMethod]
+    [DataRow(
+        """
+        [Document]
+        public class PolicyDocument : IDocument
+        {
+            public void Inbound(IInboundContext context) { context.IncludeFragment("fragment-inbound"); }
+            public void Outbound(IOutboundContext context) { context.IncludeFragment("fragment-outbound"); }
+            public void Backend(IBackendContext context) { context.IncludeFragment("fragment-backend"); }
+            public void OnError(IOnErrorContext context) { context.IncludeFragment("fragment-on-error"); }
+        }
+        """,
+        """
+        <policies>
+            <inbound>
+                <include-fragment fragment-id="fragment-inbound" />
+            </inbound>
+            <outbound>
+                <include-fragment fragment-id="fragment-outbound" />
+            </outbound>
+            <backend>
+                <include-fragment fragment-id="fragment-backend" />
+            </backend>
+            <on-error>
+                <include-fragment fragment-id="fragment-on-error" />
+            </on-error>
+        </policies>
+        """,
+        DisplayName = "Should compile include-fragment policy in sections"
+    )]
+    public void ShouldCompileIncludeFragmentPolicy(string code, string expectedXml)
+    {
+        code.CompileDocument().Should().BeSuccessful().And.DocumentEquivalentTo(expectedXml);
+    }
+}