fix: throw exception when accessing result props incorrectly

tests/AnthropicClient.Tests/Unit/Models/AnthropicResultTests.cs

@@ -11,7 +11,12 @@ public class AnthropicResultTests
     var actual = AnthropicResult<string>.Success(value, headers);
 
     actual.IsSuccess.Should().BeTrue();
+    actual.IsFailure.Should().BeFalse();
     actual.Value.Should().Be(value);
+
+    var action = () => { var _ = actual.Error; };
+    action.Should().Throw<InvalidOperationException>();
+
     actual.Headers.Should().Be(headers);
   }
 
@@ -24,7 +29,12 @@ public class AnthropicResultTests
     var actual = AnthropicResult<string>.Failure(error, headers);
 
     actual.IsSuccess.Should().BeFalse();
+    actual.IsFailure.Should().BeTrue();
     actual.Error.Should().Be(error);
+    
+    var action = () => { var _ = actual.Value; };
+    action.Should().Throw<InvalidOperationException>();
+
     actual.Headers.Should().Be(headers);
   }
 }

tests/AnthropicClient.Tests/Unit/Models/ToolCallResultTests.cs

@@ -0,0 +1,34 @@
+namespace AnthropicClient.Tests.Unit.Models;
+
+public class ToolCallResultTests
+{
+  [Fact]
+  public void Success_WhenCalled_ItShouldReturnSuccessResult()
+  {
+    var value = "success";
+
+    var actual = ToolCallResult<string>.Success(value);
+
+    actual.IsSuccess.Should().BeTrue();
+    actual.IsFailure.Should().BeFalse();
+    actual.Value.Should().Be(value);
+
+    var action = () => { var _ = actual.Error; };
+    action.Should().Throw<InvalidOperationException>();
+  }
+
+  [Fact]
+  public void Failure_WhenCalled_ItShouldReturnFailureResult()
+  {
+    var error = new Exception();
+
+    var actual = ToolCallResult<string>.Failure(error);
+
+    actual.IsSuccess.Should().BeFalse();
+    actual.IsFailure.Should().BeTrue();
+    actual.Error.Should().Be(error);
+    
+    var action = () => { var _ = actual.Value; };
+    action.Should().Throw<InvalidOperationException>();
+  }
+}

tests/AnthropicClient.Tests/Unit/Models/ToolCallTests.cs

@@ -16,7 +16,6 @@ public class ToolCallTests : SerializationTest
 
     result.IsSuccess.Should().BeTrue();
     result.Value.Should().Be("Hello, World!");
-    result.Error.Should().BeNull();
   }
 
   [Fact]
@@ -30,7 +29,6 @@ public class ToolCallTests : SerializationTest
     var result = await toolCall.InvokeAsync();
 
     result.IsSuccess.Should().BeFalse();
-    result.Value.Should().BeNull();
     result.Error.Should().NotBeNull();
   }
 
@@ -46,7 +44,6 @@ public class ToolCallTests : SerializationTest
 
     result.IsSuccess.Should().BeTrue();
     result.Value.Should().Be("Hello, World!");
-    result.Error.Should().BeNull();
   }
 
   [Fact]
@@ -60,7 +57,6 @@ public class ToolCallTests : SerializationTest
     var result = await toolCall.InvokeAsync();
 
     result.IsSuccess.Should().BeFalse();
-    result.Value.Should().BeNull();
     result.Error.Should().NotBeNull();
   }
 
@@ -78,7 +74,6 @@ public class ToolCallTests : SerializationTest
 
     result.IsSuccess.Should().BeTrue();
     result.Value.Should().Be("42");
-    result.Error.Should().BeNull();
   }
 
   [Fact]
@@ -94,7 +89,6 @@ public class ToolCallTests : SerializationTest
     var result = await toolCall.InvokeAsync();
 
     result.IsSuccess.Should().BeFalse();
-    result.Value.Should().BeNull();
     result.Error.Should().NotBeNull();
   }
 
@@ -112,7 +106,6 @@ public class ToolCallTests : SerializationTest
 
     result.IsSuccess.Should().BeTrue();
     result.Value.Should().Be("42");
-    result.Error.Should().BeNull();
   }
 
   [Fact]
@@ -128,7 +121,6 @@ public class ToolCallTests : SerializationTest
     var result = await toolCall.InvokeAsync();
 
     result.IsSuccess.Should().BeFalse();
-    result.Value.Should().BeNull();
     result.Error.Should().NotBeNull();
   }
 
@@ -146,7 +138,6 @@ public class ToolCallTests : SerializationTest
 
     result.IsSuccess.Should().BeTrue();
     result.Value.Should().Be("42");
-    result.Error.Should().BeNull();
   }
 
   [Fact]
@@ -162,7 +153,6 @@ public class ToolCallTests : SerializationTest
 
     result.IsSuccess.Should().BeTrue();
     result.Value.Should().Be("42");
-    result.Error.Should().BeNull();
   }
 
   [Fact]
@@ -177,7 +167,6 @@ public class ToolCallTests : SerializationTest
     var result = await toolCall.InvokeAsync();
 
     result.IsSuccess.Should().BeFalse();
-    result.Value.Should().BeNull();
     result.Error.Should().NotBeNull();
   }
 
@@ -195,7 +184,6 @@ public class ToolCallTests : SerializationTest
 
     result.IsSuccess.Should().BeTrue();
     result.Value.Should().Be("Monday");
-    result.Error.Should().BeNull();
   }
 
   [Fact]
@@ -219,7 +207,6 @@ public class ToolCallTests : SerializationTest
 
     result.IsSuccess.Should().BeTrue();
     result.Value.Should().Be("John");
-    result.Error.Should().BeNull();
   }
 
   [Fact]
@@ -236,7 +223,6 @@ public class ToolCallTests : SerializationTest
 
     result.IsSuccess.Should().BeTrue();
     result.Value.Should().BeNull();
-    result.Error.Should().BeNull();
   }
 
   [Fact]
@@ -253,7 +239,6 @@ public class ToolCallTests : SerializationTest
 
     result.IsSuccess.Should().BeTrue();
     result.Value.Should().BeNull();
-    result.Error.Should().BeNull();
   }
 }
 

tests/AnthropicClient.Tests/Unit/Models/ToolTests.cs

@@ -301,7 +301,7 @@ public class ToolTests : SerializationTest
     tool.DisplayName.Should().Be("Name");
     tool.Description.Should().Be("Description");
     tool.Function.Method.Name.Should().Be(nameof(ProperTool.GetWeather));
-    tool.Function.Instance.Should().BeNull();
+    tool.Function.Instance.Should().BeOfType<ProperTool>();
     tool.InputSchema.Should().BeEquivalentTo(
       expectedSchema,
       t => t.IgnoringCyclicReferences()