diff --git a/Contentstack.Management.Core.Tests/IntegrationTest/Contentstack018_EnvironmentTest.cs b/Contentstack.Management.Core.Tests/IntegrationTest/Contentstack018_EnvironmentTest.cs
new file mode 100644
index 0000000..d763b2a
--- /dev/null
+++ b/Contentstack.Management.Core.Tests/IntegrationTest/Contentstack018_EnvironmentTest.cs
@@ -0,0 +1,471 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;
+using System.Threading.Tasks;
+using Contentstack.Management.Core.Exceptions;
+using Contentstack.Management.Core.Models;
+using Contentstack.Management.Core.Tests.Helpers;
+using Contentstack.Management.Core.Tests.Model;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Newtonsoft.Json.Linq;
+
+namespace Contentstack.Management.Core.Tests.IntegrationTest
+{
+    [TestClass]
+    [DoNotParallelize]
+    public class Contentstack018_EnvironmentTest
+    {
+        /// <summary>
+        /// Name that should not exist on any stack (for negative-path tests).
+        /// </summary>
+        private const string NonExistentEnvironmentName = "nonexistent_environment_name";
+
+        private static ContentstackClient _client;
+        private Stack _stack;
+
+        [ClassInitialize]
+        public static void ClassInitialize(TestContext context)
+        {
+            _client = Contentstack.CreateAuthenticatedClient();
+        }
+
+        [ClassCleanup]
+        public static void ClassCleanup()
+        {
+            try { _client?.Logout(); } catch { }
+            _client = null;
+        }
+
+        [TestInitialize]
+        public void Initialize()
+        {
+            StackResponse response = StackResponse.getStack(_client.serializer);
+            _stack = _client.Stack(response.Stack.APIKey);
+        }
+
+        private static EnvironmentModel BuildModel(string uniqueName)
+        {
+            return new EnvironmentModel
+            {
+                Name = uniqueName,
+                Urls = new List<LocalesUrl>
+                {
+                    new LocalesUrl
+                    {
+                        Locale = "en-us",
+                        Url = "https://example.com"
+                    }
+                },
+                DeployContent = true
+            };
+        }
+
+        private static string ParseEnvironmentName(ContentstackResponse response)
+        {
+            var jo = response.OpenJObjectResponse();
+            return jo?["environment"]?["name"]?.ToString();
+        }
+
+        private void SafeDelete(string environmentName)
+        {
+            if (string.IsNullOrEmpty(environmentName))
+            {
+                return;
+            }
+
+            try
+            {
+                _stack.Environment(environmentName).Delete();
+            }
+            catch
+            {
+                // Best-effort cleanup; ignore if already deleted or API error
+            }
+        }
+
+        private static bool EnvironmentsArrayContainsName(JArray environments, string name)
+        {
+            if (environments == null || string.IsNullOrEmpty(name))
+            {
+                return false;
+            }
+
+            return environments.Any(e => e["name"]?.ToString() == name);
+        }
+
+        #region A — Sync happy path
+
+        [TestMethod]
+        public void Test001_Should_Create_Environment_Sync()
+        {
+            TestOutputLogger.LogContext("TestScenario", "Test001_Should_Create_Environment_Sync");
+            string environmentName = null;
+            string name = $"env_sync_create_{Guid.NewGuid():N}";
+            try
+            {
+                var model = BuildModel(name);
+                ContentstackResponse response = _stack.Environment().Create(model);
+
+                AssertLogger.IsTrue(response.IsSuccessStatusCode, "Create environment should succeed", "CreateSyncSuccess");
+                environmentName = ParseEnvironmentName(response);
+                AssertLogger.IsNotNull(environmentName, "environment name");
+                AssertLogger.AreEqual(name, environmentName, "Parsed name should match request", "ParsedEnvironmentName");
+
+                var jo = response.OpenJObjectResponse();
+                AssertLogger.AreEqual(name, jo["environment"]?["name"]?.ToString(), "Response name should match", "EnvironmentName");
+            }
+            finally
+            {
+                SafeDelete(environmentName ?? name);
+            }
+        }
+
+        [TestMethod]
+        public void Test002_Should_Fetch_Environment_Sync()
+        {
+            TestOutputLogger.LogContext("TestScenario", "Test002_Should_Fetch_Environment_Sync");
+            string environmentName = null;
+            string name = $"env_sync_fetch_{Guid.NewGuid():N}";
+            try
+            {
+                ContentstackResponse createResponse = _stack.Environment().Create(BuildModel(name));
+                AssertLogger.IsTrue(createResponse.IsSuccessStatusCode, "Create should succeed", "CreateForFetch");
+                environmentName = ParseEnvironmentName(createResponse);
+                AssertLogger.IsNotNull(environmentName, "name after create");
+                AssertLogger.AreEqual(name, environmentName, "Parsed name should match create request", "CreateNameMatch");
+
+                string expectedUid = createResponse.OpenJObjectResponse()?["environment"]?["uid"]?.ToString();
+
+                ContentstackResponse fetchResponse = _stack.Environment(name).Fetch();
+                AssertLogger.IsTrue(fetchResponse.IsSuccessStatusCode, "Fetch should succeed", "FetchSyncSuccess");
+
+                var env = fetchResponse.OpenJObjectResponse()?["environment"];
+                AssertLogger.AreEqual(name, env?["name"]?.ToString(), "Fetched name should match", "FetchedName");
+                AssertLogger.AreEqual(expectedUid, env?["uid"]?.ToString(), "Fetched uid should match create response", "FetchedUid");
+            }
+            finally
+            {
+                SafeDelete(environmentName ?? name);
+            }
+        }
+
+        [TestMethod]
+        public void Test003_Should_Query_Environments_Sync()
+        {
+            TestOutputLogger.LogContext("TestScenario", "Test003_Should_Query_Environments_Sync");
+            string environmentName = null;
+            string name = $"env_sync_query_{Guid.NewGuid():N}";
+            try
+            {
+                ContentstackResponse createResponse = _stack.Environment().Create(BuildModel(name));
+                AssertLogger.IsTrue(createResponse.IsSuccessStatusCode, "Create should succeed", "CreateForQuery");
+                environmentName = ParseEnvironmentName(createResponse);
+                AssertLogger.IsNotNull(environmentName, "name after create");
+
+                ContentstackResponse queryResponse = _stack.Environment().Query().Find();
+                AssertLogger.IsTrue(queryResponse.IsSuccessStatusCode, "Query Find should succeed", "QueryFindSuccess");
+
+                var environments = queryResponse.OpenJObjectResponse()?["environments"] as JArray;
+                AssertLogger.IsNotNull(environments, "environments array");
+                AssertLogger.IsTrue(
+                    EnvironmentsArrayContainsName(environments, name),
+                    "Query result should contain created environment name",
+                    "ContainsName");
+            }
+            finally
+            {
+                SafeDelete(environmentName ?? name);
+            }
+        }
+
+        [TestMethod]
+        public void Test004_Should_Update_Environment_Sync()
+        {
+            TestOutputLogger.LogContext("TestScenario", "Test004_Should_Update_Environment_Sync");
+            string environmentNameForCleanup = null;
+            string originalName = $"env_sync_update_{Guid.NewGuid():N}";
+            string updatedName = $"{originalName}_updated";
+            try
+            {
+                ContentstackResponse createResponse = _stack.Environment().Create(BuildModel(originalName));
+                AssertLogger.IsTrue(createResponse.IsSuccessStatusCode, "Create should succeed", "CreateForUpdate");
+                string createdName = ParseEnvironmentName(createResponse);
+                AssertLogger.IsNotNull(createdName, "name after create");
+                AssertLogger.AreEqual(originalName, createdName, "Parsed name should match create request", "CreateNameMatch");
+
+                var updateModel = BuildModel(updatedName);
+                ContentstackResponse updateResponse = _stack.Environment(originalName).Update(updateModel);
+                AssertLogger.IsTrue(updateResponse.IsSuccessStatusCode, "Update should succeed", "UpdateSyncSuccess");
+
+                environmentNameForCleanup = updatedName;
+
+                ContentstackResponse fetchResponse = _stack.Environment(updatedName).Fetch();
+                AssertLogger.IsTrue(fetchResponse.IsSuccessStatusCode, "Fetch after update should succeed", "FetchAfterUpdate");
+                var env = fetchResponse.OpenJObjectResponse()?["environment"];
+                AssertLogger.AreEqual(updatedName, env?["name"]?.ToString(), "Name should reflect update", "UpdatedName");
+            }
+            finally
+            {
+                SafeDelete(environmentNameForCleanup ?? originalName);
+            }
+        }
+
+        [TestMethod]
+        public void Test005_Should_Delete_Environment_Sync()
+        {
+            TestOutputLogger.LogContext("TestScenario", "Test005_Should_Delete_Environment_Sync");
+            string environmentName = null;
+            string name = $"env_sync_delete_{Guid.NewGuid():N}";
+            try
+            {
+                ContentstackResponse createResponse = _stack.Environment().Create(BuildModel(name));
+                AssertLogger.IsTrue(createResponse.IsSuccessStatusCode, "Create should succeed", "CreateForDelete");
+                environmentName = ParseEnvironmentName(createResponse);
+                AssertLogger.IsNotNull(environmentName, "name after create");
+
+                ContentstackResponse deleteResponse = _stack.Environment(name).Delete();
+                AssertLogger.IsTrue(deleteResponse.IsSuccessStatusCode, "Delete should succeed", "DeleteSyncSuccess");
+
+                AssertLogger.ThrowsContentstackError(
+                    () => _stack.Environment(name).Fetch(),
+                    "FetchAfterDelete",
+                    HttpStatusCode.NotFound,
+                    (HttpStatusCode)422);
+
+                environmentName = null;
+            }
+            finally
+            {
+                SafeDelete(environmentName ?? name);
+            }
+        }
+
+        #endregion
+
+        #region B — Async happy path
+
+        [TestMethod]
+        public async Task Test006_Should_Create_Environment_Async()
+        {
+            TestOutputLogger.LogContext("TestScenario", "Test006_Should_Create_Environment_Async");
+            string environmentName = null;
+            string name = $"env_async_create_{Guid.NewGuid():N}";
+            try
+            {
+                var model = BuildModel(name);
+                ContentstackResponse response = await _stack.Environment().CreateAsync(model);
+
+                AssertLogger.IsTrue(response.IsSuccessStatusCode, "CreateAsync should succeed", "CreateAsyncSuccess");
+                environmentName = ParseEnvironmentName(response);
+                AssertLogger.IsNotNull(environmentName, "environment name");
+                AssertLogger.AreEqual(name, environmentName, "Parsed name should match request", "ParsedEnvironmentName");
+
+                var jo = response.OpenJObjectResponse();
+                AssertLogger.AreEqual(name, jo["environment"]?["name"]?.ToString(), "Response name should match", "EnvironmentName");
+            }
+            finally
+            {
+                SafeDelete(environmentName ?? name);
+            }
+        }
+
+        [TestMethod]
+        public async Task Test007_Should_Fetch_Environment_Async()
+        {
+            TestOutputLogger.LogContext("TestScenario", "Test007_Should_Fetch_Environment_Async");
+            string environmentName = null;
+            string name = $"env_async_fetch_{Guid.NewGuid():N}";
+            try
+            {
+                ContentstackResponse createResponse = await _stack.Environment().CreateAsync(BuildModel(name));
+                AssertLogger.IsTrue(createResponse.IsSuccessStatusCode, "Create should succeed", "CreateForFetchAsync");
+                environmentName = ParseEnvironmentName(createResponse);
+                AssertLogger.IsNotNull(environmentName, "name after create");
+                AssertLogger.AreEqual(name, environmentName, "Parsed name should match create request", "CreateNameMatch");
+
+                string expectedUid = createResponse.OpenJObjectResponse()?["environment"]?["uid"]?.ToString();
+
+                ContentstackResponse fetchResponse = await _stack.Environment(name).FetchAsync();
+                AssertLogger.IsTrue(fetchResponse.IsSuccessStatusCode, "FetchAsync should succeed", "FetchAsyncSuccess");
+
+                var env = fetchResponse.OpenJObjectResponse()?["environment"];
+                AssertLogger.AreEqual(name, env?["name"]?.ToString(), "Fetched name should match", "FetchedName");
+                AssertLogger.AreEqual(expectedUid, env?["uid"]?.ToString(), "Fetched uid should match create response", "FetchedUid");
+            }
+            finally
+            {
+                SafeDelete(environmentName ?? name);
+            }
+        }
+
+        [TestMethod]
+        public async Task Test008_Should_Query_Environments_Async()
+        {
+            TestOutputLogger.LogContext("TestScenario", "Test008_Should_Query_Environments_Async");
+            string environmentName = null;
+            string name = $"env_async_query_{Guid.NewGuid():N}";
+            try
+            {
+                ContentstackResponse createResponse = await _stack.Environment().CreateAsync(BuildModel(name));
+                AssertLogger.IsTrue(createResponse.IsSuccessStatusCode, "Create should succeed", "CreateForQueryAsync");
+                environmentName = ParseEnvironmentName(createResponse);
+                AssertLogger.IsNotNull(environmentName, "name after create");
+
+                ContentstackResponse queryResponse = await _stack.Environment().Query().FindAsync();
+                AssertLogger.IsTrue(queryResponse.IsSuccessStatusCode, "Query FindAsync should succeed", "QueryFindAsyncSuccess");
+
+                var environments = queryResponse.OpenJObjectResponse()?["environments"] as JArray;
+                AssertLogger.IsNotNull(environments, "environments array");
+                AssertLogger.IsTrue(
+                    EnvironmentsArrayContainsName(environments, name),
+                    "Query result should contain created environment name",
+                    "ContainsName");
+            }
+            finally
+            {
+                SafeDelete(environmentName ?? name);
+            }
+        }
+
+        [TestMethod]
+        public async Task Test009_Should_Update_Environment_Async()
+        {
+            TestOutputLogger.LogContext("TestScenario", "Test009_Should_Update_Environment_Async");
+            string environmentNameForCleanup = null;
+            string originalName = $"env_async_update_{Guid.NewGuid():N}";
+            string updatedName = $"{originalName}_updated";
+            try
+            {
+                ContentstackResponse createResponse = await _stack.Environment().CreateAsync(BuildModel(originalName));
+                AssertLogger.IsTrue(createResponse.IsSuccessStatusCode, "Create should succeed", "CreateForUpdateAsync");
+                string createdName = ParseEnvironmentName(createResponse);
+                AssertLogger.IsNotNull(createdName, "name after create");
+                AssertLogger.AreEqual(originalName, createdName, "Parsed name should match create request", "CreateNameMatch");
+
+                var updateModel = BuildModel(updatedName);
+                ContentstackResponse updateResponse = await _stack.Environment(originalName).UpdateAsync(updateModel);
+                AssertLogger.IsTrue(updateResponse.IsSuccessStatusCode, "UpdateAsync should succeed", "UpdateAsyncSuccess");
+
+                environmentNameForCleanup = updatedName;
+
+                ContentstackResponse fetchResponse = await _stack.Environment(updatedName).FetchAsync();
+                AssertLogger.IsTrue(fetchResponse.IsSuccessStatusCode, "FetchAsync after update should succeed", "FetchAsyncAfterUpdate");
+                var env = fetchResponse.OpenJObjectResponse()?["environment"];
+                AssertLogger.AreEqual(updatedName, env?["name"]?.ToString(), "Name should reflect update", "UpdatedName");
+            }
+            finally
+            {
+                SafeDelete(environmentNameForCleanup ?? originalName);
+            }
+        }
+
+        [TestMethod]
+        public async Task Test010_Should_Delete_Environment_Async()
+        {
+            TestOutputLogger.LogContext("TestScenario", "Test010_Should_Delete_Environment_Async");
+            string environmentName = null;
+            string name = $"env_async_delete_{Guid.NewGuid():N}";
+            try
+            {
+                ContentstackResponse createResponse = await _stack.Environment().CreateAsync(BuildModel(name));
+                AssertLogger.IsTrue(createResponse.IsSuccessStatusCode, "Create should succeed", "CreateForDeleteAsync");
+                environmentName = ParseEnvironmentName(createResponse);
+                AssertLogger.IsNotNull(environmentName, "name after create");
+
+                ContentstackResponse deleteResponse = await _stack.Environment(name).DeleteAsync();
+                AssertLogger.IsTrue(deleteResponse.IsSuccessStatusCode, "DeleteAsync should succeed", "DeleteAsyncSuccess");
+
+                await AssertLogger.ThrowsContentstackErrorAsync(
+                    async () => await _stack.Environment(name).FetchAsync(),
+                    "FetchAsyncAfterDelete",
+                    HttpStatusCode.NotFound,
+                    (HttpStatusCode)422);
+
+                environmentName = null;
+            }
+            finally
+            {
+                SafeDelete(environmentName ?? name);
+            }
+        }
+
+        #endregion
+
+        #region C — Sync negative path
+
+        [TestMethod]
+        public void Test011_Should_Fail_Fetch_NonExistent_Environment_Sync()
+        {
+            TestOutputLogger.LogContext("TestScenario", "Test011_Should_Fail_Fetch_NonExistent_Environment_Sync");
+            AssertLogger.ThrowsContentstackError(
+                () => _stack.Environment(NonExistentEnvironmentName).Fetch(),
+                "FetchNonExistentSync",
+                HttpStatusCode.NotFound,
+                (HttpStatusCode)422);
+        }
+
+        [TestMethod]
+        public void Test012_Should_Fail_Update_NonExistent_Environment_Sync()
+        {
+            TestOutputLogger.LogContext("TestScenario", "Test012_Should_Fail_Update_NonExistent_Environment_Sync");
+            var model = BuildModel($"env_nonexistent_update_{Guid.NewGuid():N}");
+            AssertLogger.ThrowsContentstackError(
+                () => _stack.Environment(NonExistentEnvironmentName).Update(model),
+                "UpdateNonExistentSync",
+                HttpStatusCode.NotFound,
+                (HttpStatusCode)422);
+        }
+
+        [TestMethod]
+        public void Test013_Should_Fail_Delete_NonExistent_Environment_Sync()
+        {
+            TestOutputLogger.LogContext("TestScenario", "Test013_Should_Fail_Delete_NonExistent_Environment_Sync");
+            AssertLogger.ThrowsContentstackError(
+                () => _stack.Environment(NonExistentEnvironmentName).Delete(),
+                "DeleteNonExistentSync",
+                HttpStatusCode.NotFound,
+                (HttpStatusCode)422);
+        }
+
+        #endregion
+
+        #region D — Async negative path
+
+        [TestMethod]
+        public async Task Test014_Should_Fail_Fetch_NonExistent_Environment_Async()
+        {
+            TestOutputLogger.LogContext("TestScenario", "Test014_Should_Fail_Fetch_NonExistent_Environment_Async");
+            await AssertLogger.ThrowsContentstackErrorAsync(
+                async () => await _stack.Environment(NonExistentEnvironmentName).FetchAsync(),
+                "FetchNonExistentAsync",
+                HttpStatusCode.NotFound,
+                (HttpStatusCode)422);
+        }
+
+        [TestMethod]
+        public async Task Test015_Should_Fail_Update_NonExistent_Environment_Async()
+        {
+            TestOutputLogger.LogContext("TestScenario", "Test015_Should_Fail_Update_NonExistent_Environment_Async");
+            var model = BuildModel($"env_nonexistent_update_async_{Guid.NewGuid():N}");
+            await AssertLogger.ThrowsContentstackErrorAsync(
+                async () => await _stack.Environment(NonExistentEnvironmentName).UpdateAsync(model),
+                "UpdateNonExistentAsync",
+                HttpStatusCode.NotFound,
+                (HttpStatusCode)422);
+        }
+
+        [TestMethod]
+        public async Task Test016_Should_Fail_Delete_NonExistent_Environment_Async()
+        {
+            TestOutputLogger.LogContext("TestScenario", "Test016_Should_Fail_Delete_NonExistent_Environment_Async");
+            await AssertLogger.ThrowsContentstackErrorAsync(
+                async () => await _stack.Environment(NonExistentEnvironmentName).DeleteAsync(),
+                "DeleteNonExistentAsync",
+                HttpStatusCode.NotFound,
+                (HttpStatusCode)422);
+        }
+
+        #endregion
+    }
+}