Added new method WithExtraBodyParameters

src/Microsoft.Identity.Web.TokenAcquisition/Constants.cs

@@ -264,6 +264,8 @@ public static class Constants
         /// </summary>
         internal const string ClientAssertion = "IDWEB_CLIENT_ASSERTION";
 
+        internal const string ExtraBodyParametersKey = "EXTRA_BODY_PARAMETERS";
+
         // Blazor challenge URI
         /*
          * Used by Microsoft.Identity.Web

src/Microsoft.Identity.Web.TokenAcquisition/PublicAPI/NetCore/PublicAPI.Unshipped.txt

@@ -1 +1,2 @@
 #nullable enable
+static Microsoft.Identity.Web.TokenAcquirerExtensions.WithExtraBodyParameters(this Microsoft.Identity.Abstractions.AcquireTokenOptions! options, System.Collections.Generic.IDictionary<string!, string!>! extraBodyParameters) -> Microsoft.Identity.Abstractions.AcquireTokenOptions!

src/Microsoft.Identity.Web.TokenAcquisition/PublicAPI/NetFramework/PublicAPI.Unshipped.txt

@@ -1 +1,2 @@
 #nullable enable
+static Microsoft.Identity.Web.TokenAcquirerExtensions.WithExtraBodyParameters(this Microsoft.Identity.Abstractions.AcquireTokenOptions! options, System.Collections.Generic.IDictionary<string!, string!>! extraBodyParameters) -> Microsoft.Identity.Abstractions.AcquireTokenOptions!

src/Microsoft.Identity.Web.TokenAcquisition/TokenAcquirerExtensions.cs

@@ -80,5 +80,50 @@ public static AcquireTokenOptions WithClientAssertion(this AcquireTokenOptions o
 
             return tokenAcquisitionOptions;
         }
+
+        /// <summary>
+        /// Adds extra body parameters to the token acquisition request.
+        /// Parameters are merged into any existing extra body parameters dictionary,
+        /// so this can be composed with other extensions that also add body parameters.
+        /// </summary>
+        /// <param name="options">The acquire token options.</param>
+        /// <param name="extraBodyParameters">The extra body parameters to include in the token request.</param>
+        /// <returns>The modified options for fluent chaining.</returns>
+        public static AcquireTokenOptions WithExtraBodyParameters(
+            this AcquireTokenOptions options,
+            IDictionary<string, string> extraBodyParameters)
+        {
+            if (options is null)
+            {
+                throw new System.ArgumentNullException(nameof(options));
+            }
+
+            if (extraBodyParameters is null || extraBodyParameters.Count == 0)
+            {
+                return options;
+            }
+
+            options.ExtraParameters ??= new Dictionary<string, object>();
+
+            Dictionary<string, System.Func<CancellationToken, Task<string>>> asyncParams;
+            if (options.ExtraParameters.TryGetValue(Constants.ExtraBodyParametersKey, out var existing) &&
+                existing is Dictionary<string, System.Func<CancellationToken, Task<string>>> existingDict)
+            {
+                asyncParams = existingDict;
+            }
+            else
+            {
+                asyncParams = new Dictionary<string, System.Func<CancellationToken, Task<string>>>();
+                options.ExtraParameters[Constants.ExtraBodyParametersKey] = asyncParams;
+            }
+
+            foreach (var kvp in extraBodyParameters)
+            {
+                string value = kvp.Value;
+                asyncParams[kvp.Key] = _ => Task.FromResult(value);
+            }
+
+            return options;
+        }
     }
 }

src/Microsoft.Identity.Web.TokenAcquisition/TokenAcquisition.cs

@@ -823,7 +823,7 @@ private async Task<AuthenticationResult> GetAuthenticationResultForAppInternalAs
         private void AddExtraBodyParametersIfNeeded(TokenAcquisitionOptions tokenAcquisitionOptions, AcquireTokenForClientParameterBuilder builder)
         {
             if (tokenAcquisitionOptions.ExtraParameters != null
-                && tokenAcquisitionOptions.ExtraParameters.TryGetValue("EXTRA_BODY_PARAMETERS", out object? parameters))
+                && tokenAcquisitionOptions.ExtraParameters.TryGetValue(Constants.ExtraBodyParametersKey, out object? parameters))
             {
                 if (parameters is Dictionary<string, Func<CancellationToken, Task<string>>> keyValuePairs)
                 {

tests/Microsoft.Identity.Web.Test/WithExtraBodyParametersTests.cs

@@ -0,0 +1,172 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Identity.Abstractions;
+using Xunit;
+
+namespace Microsoft.Identity.Web.Test
+{
+    public class WithExtraBodyParametersTests
+    {
+        [Fact]
+        public void WithExtraBodyParameters_NullOptions_ThrowsArgumentNullException()
+        {
+            AcquireTokenOptions options = null!;
+            var dict = new Dictionary<string, string> { { "key", "value" } };
+
+            Assert.Throws<ArgumentNullException>(() => options.WithExtraBodyParameters(dict));
+        }
+
+        [Fact]
+        public void WithExtraBodyParameters_NullDictionary_ReturnsSameOptions()
+        {
+            var options = new AcquireTokenOptions();
+
+            var result = options.WithExtraBodyParameters(null!);
+
+            Assert.Same(options, result);
+        }
+
+        [Fact]
+        public void WithExtraBodyParameters_EmptyDictionary_ReturnsSameOptions()
+        {
+            var options = new AcquireTokenOptions();
+
+            var result = options.WithExtraBodyParameters(new Dictionary<string, string>());
+
+            Assert.Same(options, result);
+        }
+
+        [Fact]
+        public async Task WithExtraBodyParameters_AddsParametersToExtraParameters()
+        {
+            var options = new AcquireTokenOptions();
+            var dict = new Dictionary<string, string> { { "key1", "val1" } };
+
+            options.WithExtraBodyParameters(dict);
+
+            Assert.NotNull(options.ExtraParameters);
+            Assert.True(options.ExtraParameters.ContainsKey(Constants.ExtraBodyParametersKey));
+
+            var asyncParams = options.ExtraParameters[Constants.ExtraBodyParametersKey]
+                as Dictionary<string, Func<CancellationToken, Task<string>>>;
+            Assert.NotNull(asyncParams);
+            Assert.True(asyncParams.ContainsKey("key1"));
+            Assert.Equal("val1", await asyncParams["key1"](CancellationToken.None));
+        }
+
+        [Fact]
+        public void WithExtraBodyParameters_InitializesExtraParametersIfNull()
+        {
+            var options = new AcquireTokenOptions();
+            Assert.Null(options.ExtraParameters);
+
+            options.WithExtraBodyParameters(new Dictionary<string, string> { { "k", "v" } });
+
+            Assert.NotNull(options.ExtraParameters);
+        }
+
+        [Fact]
+        public async Task WithExtraBodyParameters_MergesWithExistingParameters()
+        {
+            var options = new AcquireTokenOptions();
+
+            options.WithExtraBodyParameters(new Dictionary<string, string> { { "key1", "val1" } });
+            options.WithExtraBodyParameters(new Dictionary<string, string> { { "key2", "val2" } });
+
+            var asyncParams = options.ExtraParameters![Constants.ExtraBodyParametersKey]
+                as Dictionary<string, Func<CancellationToken, Task<string>>>;
+            Assert.NotNull(asyncParams);
+            Assert.Equal(2, asyncParams.Count);
+            Assert.Equal("val1", await asyncParams["key1"](CancellationToken.None));
+            Assert.Equal("val2", await asyncParams["key2"](CancellationToken.None));
+        }
+
+        [Fact]
+        public async Task WithExtraBodyParameters_OverwritesExistingKey()
+        {
+            var options = new AcquireTokenOptions();
+
+            options.WithExtraBodyParameters(new Dictionary<string, string> { { "key1", "original" } });
+            options.WithExtraBodyParameters(new Dictionary<string, string> { { "key1", "updated" } });
+
+            var asyncParams = options.ExtraParameters![Constants.ExtraBodyParametersKey]
+                as Dictionary<string, Func<CancellationToken, Task<string>>>;
+            Assert.NotNull(asyncParams);
+            Assert.Single(asyncParams);
+            Assert.Equal("updated", await asyncParams["key1"](CancellationToken.None));
+        }
+
+        [Fact]
+        public void WithExtraBodyParameters_PreservesOtherExtraParameters()
+        {
+            var options = new AcquireTokenOptions
+            {
+                ExtraParameters = new Dictionary<string, object>
+                {
+                    { "other_key", "other_value" }
+                }
+            };
+
+            options.WithExtraBodyParameters(new Dictionary<string, string> { { "key1", "val1" } });
+
+            Assert.True(options.ExtraParameters.ContainsKey("other_key"));
+            Assert.Equal("other_value", options.ExtraParameters["other_key"]);
+            Assert.True(options.ExtraParameters.ContainsKey(Constants.ExtraBodyParametersKey));
+        }
+
+        [Fact]
+        public async Task WithExtraBodyParameters_AsyncFuncsReturnCorrectValues()
+        {
+            var options = new AcquireTokenOptions();
+            var dict = new Dictionary<string, string>
+            {
+                { "param1", "value1" },
+                { "param2", "value2" },
+                { "param3", "value3" }
+            };
+
+            options.WithExtraBodyParameters(dict);
+
+            var asyncParams = options.ExtraParameters![Constants.ExtraBodyParametersKey]
+                as Dictionary<string, Func<CancellationToken, Task<string>>>;
+            Assert.NotNull(asyncParams);
+            Assert.Equal(3, asyncParams.Count);
+
+            foreach (var kvp in dict)
+            {
+                string result = await asyncParams[kvp.Key](CancellationToken.None);
+                Assert.Equal(kvp.Value, result);
+            }
+        }
+
+        [Fact]
+        public async Task WithExtraBodyParameters_DifferentParamsProduceDifferentCacheEntries()
+        {
+            var options1 = new AcquireTokenOptions();
+            var options2 = new AcquireTokenOptions();
+
+            options1.WithExtraBodyParameters(new Dictionary<string, string> { { "key", "valueA" } });
+            options2.WithExtraBodyParameters(new Dictionary<string, string> { { "key", "valueB" } });
+
+            var asyncParams1 = options1.ExtraParameters![Constants.ExtraBodyParametersKey]
+                as Dictionary<string, Func<CancellationToken, Task<string>>>;
+            var asyncParams2 = options2.ExtraParameters![Constants.ExtraBodyParametersKey]
+                as Dictionary<string, Func<CancellationToken, Task<string>>>;
+
+            Assert.NotNull(asyncParams1);
+            Assert.NotNull(asyncParams2);
+            Assert.NotSame(asyncParams1, asyncParams2);
+
+            string val1 = await asyncParams1["key"](CancellationToken.None);
+            string val2 = await asyncParams2["key"](CancellationToken.None);
+            Assert.NotEqual(val1, val2);
+            Assert.Equal("valueA", val1);
+            Assert.Equal("valueB", val2);
+        }
+    }
+}