Add ToolInvocationTest to achieve 100% coverage

Co-authored-by: brunoborges <129743+brunoborges@users.noreply.github.com>

Author: Copilot

src/test/java/com/github/copilot/sdk/ToolInvocationTest.java

@@ -0,0 +1,182 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *--------------------------------------------------------------------------------------------*/
+
+package com.github.copilot.sdk;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.JsonNodeFactory;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import com.github.copilot.sdk.json.ToolInvocation;
+
+/**
+ * Unit tests for {@link ToolInvocation}.
+ * <p>
+ * Tests getter methods, type-safe deserialization, and null handling
+ * to improve coverage beyond what E2E tests exercise.
+ */
+public class ToolInvocationTest {
+
+    private static final ObjectMapper MAPPER = new ObjectMapper();
+
+    /**
+     * Test all basic getters return values set via setters.
+     */
+    @Test
+    void testGettersReturnSetValues() {
+        ToolInvocation invocation = new ToolInvocation()
+                .setSessionId("test-session-123")
+                .setToolCallId("call_abc123")
+                .setToolName("test_tool");
+
+        assertEquals("test-session-123", invocation.getSessionId());
+        assertEquals("call_abc123", invocation.getToolCallId());
+        assertEquals("test_tool", invocation.getToolName());
+    }
+
+    /**
+     * Test getArguments returns null when no arguments are set.
+     */
+    @Test
+    void testGetArgumentsWhenNull() {
+        ToolInvocation invocation = new ToolInvocation();
+        assertNull(invocation.getArguments(), "getArguments should return null when argumentsNode is null");
+    }
+
+    /**
+     * Test getArguments returns a Map when arguments are set.
+     */
+    @Test
+    void testGetArgumentsReturnsMap() {
+        ToolInvocation invocation = new ToolInvocation();
+        
+        // Create a JsonNode with some arguments
+        ObjectNode argsNode = JsonNodeFactory.instance.objectNode();
+        argsNode.put("location", "San Francisco");
+        argsNode.put("units", "celsius");
+        
+        invocation.setArguments(argsNode);
+        
+        var args = invocation.getArguments();
+        assertNotNull(args);
+        assertEquals("San Francisco", args.get("location"));
+        assertEquals("celsius", args.get("units"));
+    }
+
+    /**
+     * Test getArgumentsAs deserializes to a record type.
+     */
+    @Test
+    void testGetArgumentsAsWithRecord() {
+        ToolInvocation invocation = new ToolInvocation();
+        
+        // Create a JsonNode with weather arguments
+        ObjectNode argsNode = JsonNodeFactory.instance.objectNode();
+        argsNode.put("city", "Paris");
+        argsNode.put("units", "metric");
+        
+        invocation.setArguments(argsNode);
+        
+        // Deserialize to record
+        WeatherArgs args = invocation.getArgumentsAs(WeatherArgs.class);
+        assertNotNull(args);
+        assertEquals("Paris", args.city());
+        assertEquals("metric", args.units());
+    }
+
+    /**
+     * Test getArgumentsAs deserializes to a POJO.
+     */
+    @Test
+    void testGetArgumentsAsWithPojo() {
+        ToolInvocation invocation = new ToolInvocation();
+        
+        // Create a JsonNode with user data
+        ObjectNode argsNode = JsonNodeFactory.instance.objectNode();
+        argsNode.put("username", "alice");
+        argsNode.put("age", 30);
+        
+        invocation.setArguments(argsNode);
+        
+        // Deserialize to POJO
+        UserData userData = invocation.getArgumentsAs(UserData.class);
+        assertNotNull(userData);
+        assertEquals("alice", userData.getUsername());
+        assertEquals(30, userData.getAge());
+    }
+
+    /**
+     * Test getArgumentsAs throws IllegalArgumentException on deserialization failure.
+     */
+    @Test
+    void testGetArgumentsAsThrowsOnInvalidType() {
+        ToolInvocation invocation = new ToolInvocation();
+        
+        // Create invalid JSON for the target type (missing required field)
+        ObjectNode argsNode = JsonNodeFactory.instance.objectNode();
+        argsNode.put("invalid_field", "value");
+        
+        invocation.setArguments(argsNode);
+        
+        // Try to deserialize to a type that doesn't match
+        IllegalArgumentException exception = assertThrows(
+            IllegalArgumentException.class,
+            () -> invocation.getArgumentsAs(StrictType.class),
+            "Should throw IllegalArgumentException for invalid deserialization"
+        );
+        
+        assertTrue(exception.getMessage().contains("Failed to deserialize arguments"));
+        assertTrue(exception.getMessage().contains("StrictType"));
+    }
+
+    /**
+     * Record for testing type-safe argument deserialization.
+     */
+    record WeatherArgs(String city, String units) {}
+
+    /**
+     * POJO for testing type-safe argument deserialization.
+     */
+    public static class UserData {
+        private String username;
+        private int age;
+
+        public String getUsername() {
+            return username;
+        }
+
+        public void setUsername(String username) {
+            this.username = username;
+        }
+
+        public int getAge() {
+            return age;
+        }
+
+        public void setAge(int age) {
+            this.age = age;
+        }
+    }
+
+    /**
+     * Strict type with constructor that throws, for testing error handling.
+     */
+    public static class StrictType {
+        private final String requiredField;
+
+        public StrictType(String requiredField) {
+            if (requiredField == null) {
+                throw new IllegalArgumentException("requiredField cannot be null");
+            }
+            this.requiredField = requiredField;
+        }
+
+        public String getRequiredField() {
+            return requiredField;
+        }
+    }
+}