diff --git a/README.md b/README.md
index 2baadc1..72005db 100644
--- a/README.md
+++ b/README.md
@@ -9,11 +9,14 @@ endpoints :
 * `POST /items`: creates an item
 * `GET /items`: returns the list of items
 
-## Usage
+## Running and testing
 
 This project uses Leiningen. Assuming you already have Leiningen installed,
 running the API should be as easy as cloning the repo and issuing `lein run`. By
-default, the server listens on port 3000.
+default, the server listens on port 3000. To explore the API using Swagger UI,
+you can head to <http://localhost:3000/doc>.
+
+To run the unit and integration tests: `lein test`
 
 ## Structure
 
@@ -48,3 +51,4 @@ The following links proved more than useful when working on this assignment:
 * <https://cljdoc.org/d/com.github.seancorfield/next.jdbc/1.3.1086/doc/getting-started>
 * <https://cljdoc.org/d/metosin/reitit/0.10.0/doc/ring/swagger-support>
 * <https://www.baeldung.com/clojure-ring>
+* <https://practical.li/clojure/testing/unit-testing/>
diff --git a/project.clj b/project.clj
index cea8d79..d8dfa3b 100644
--- a/project.clj
+++ b/project.clj
@@ -12,7 +12,8 @@
                  [metosin/reitit-swagger-ui "0.10.0"]
                  [metosin/muuntaja "0.6.11"]
                  [com.github.seancorfield/next.jdbc "1.3.1086"]
-                 [org.xerial/sqlite-jdbc "3.51.1.0"]]
+                 [org.xerial/sqlite-jdbc "3.51.1.0"]
+                 [org.clojure/data.json "2.5.1"]]
   :main ^:skip-aot yohoho.app
   :target-path "target/%s"
   :profiles {:uberjar {:aot :all
diff --git a/test/yohoho/db_test.clj b/test/yohoho/db_test.clj
new file mode 100644
index 0000000..be0c264
--- /dev/null
+++ b/test/yohoho/db_test.clj
@@ -0,0 +1,106 @@
+(ns yohoho.db-test
+  (:require
+   [clojure.test :refer :all]
+   [next.jdbc :as jdbc]
+   [yohoho.db :as db]))
+
+;; In-memory database setup ---------------------------------------
+(def schema-sql
+  "CREATE TABLE items (
+     id INTEGER PRIMARY KEY,
+     name TEXT NOT NULL,
+     email TEXT NOT NULL
+   );")
+
+(defn with-memory-db [f]
+  (let [conn (jdbc/get-connection
+              {:dbtype "sqlite"
+               :dbname ":memory:"})]
+    ;; create schema on the SAME connection
+    (jdbc/execute! conn [schema-sql])
+
+    ;; force db.clj to reuse this connection
+    (with-redefs [db/db conn]
+      (f))
+
+    (.close conn)))
+
+(use-fixtures :each with-memory-db)
+
+;; Tests ----------------------------------------------------------
+(deftest test-init
+  (testing "Database initialization creates items table"
+    ;; Drop the table first to test initialization
+    (try
+      (jdbc/execute! db/db ["DROP TABLE IF EXISTS items"])
+      (catch Exception _))
+    (db/init!)
+    ;; Verify table exists by trying to query it
+    (is (vector? (db/get-all-items)))))
+
+
+(deftest test-store-item
+  (testing "Storing item returns an ID"
+    (let [id (db/store-item! "Test Item" "test@example.com")]
+      (is (number? id))
+      (is (> id 0))))
+
+  (testing "Stored item can be retrieved"
+    (let [id (db/store-item! "Test Item" "test@example.com")
+          item (db/get-item id)]
+      (is (= "Test Item" (:name item)))
+      (is (= "test@example.com" (:email item)))
+      (is (= id (:id item)))))
+
+  (testing "Multiple items get unique IDs"
+    (let [id1 (db/store-item! "Item 1" "item1@example.com")
+          id2 (db/store-item! "Item 2" "item2@example.com")]
+      (is (not= id1 id2)))))
+
+
+(deftest test-get-item
+  (testing "Getting non-existent item returns nil"
+    (is (nil? (db/get-item 999))))
+
+  (testing "Getting existing item returns map with correct keys"
+    (let [id (db/store-item! "Test" "test@example.com")
+          item (db/get-item id)]
+      (is (map? item))
+      (is (contains? item :id))
+      (is (contains? item :name))
+      (is (contains? item :email))
+      ;; Keys should be unqualified
+      (is (not (qualified-keyword? :id)))
+      (is (not (qualified-keyword? :name)))
+      (is (not (qualified-keyword? :email)))))
+
+  (testing "Retrieved item has correct values"
+    (let [id (db/store-item! "My Item" "myitem@example.com")
+          item (db/get-item id)]
+      (is (= id (:id item)))
+      (is (= "My Item" (:name item)))
+      (is (= "myitem@example.com" (:email item))))))
+
+
+(deftest test-get-all-items
+  (testing "Empty database returns empty vector"
+    (is (= [] (db/get-all-items))))
+
+  (testing "Database with items returns all items"
+    (db/store-item! "Item 1" "item1@example.com")
+    (db/store-item! "Item 2" "item2@example.com")
+    (db/store-item! "Item 3" "item3@example.com")
+    (let [items (db/get-all-items)]
+      (is (= 3 (count items)))
+      (is (every? map? items))
+      (is (every? #(contains? % :id) items))
+      (is (every? #(contains? % :name) items))
+      (is (every? #(contains? % :email) items))))
+
+  (testing "Items are returned with unqualified keys"
+    (db/store-item! "Test" "test@example.com")
+    (let [items (db/get-all-items)
+          item (first items)]
+      (is (not (qualified-keyword? :id)))
+      (is (not (qualified-keyword? :name)))
+      (is (not (qualified-keyword? :email))))))
diff --git a/test/yohoho/handlers_test.clj b/test/yohoho/handlers_test.clj
new file mode 100644
index 0000000..f111ef8
--- /dev/null
+++ b/test/yohoho/handlers_test.clj
@@ -0,0 +1,65 @@
+(ns yohoho.handlers-test
+  (:require [clojure.test :refer :all]
+            [yohoho.handlers :as handler]
+            [yohoho.db :as db]))
+
+(deftest test-ahoy
+  (testing "Health check endpoint returns 200"
+    (let [response (handler/ahoy {})]
+      (is (= 200 (:status response)))
+      (is (string? (:body response)))
+      (is (re-find #"Ahoy" (:body response))))))
+
+(deftest test-get-items
+  (testing "Getting all items returns proper structure"
+    (with-redefs [db/get-all-items (fn [] [{:id 1 :name "Test" :email "test@example.org"}
+                                           {:id 2 :name "Test2" :email "test2@example.org"}])]
+      (let [response (handler/get-items {})]
+        (is (= 200 (:status response)))
+        (is (map? (:body response)))
+        (is (vector? (get-in response [:body :items])))
+        (is (= 2 (count (get-in response [:body :items])))))))
+
+  (testing "Getting items with empty database"
+    (with-redefs [db/get-all-items (fn [] [])]
+      (let [response (handler/get-items {})]
+        (is (= 200 (:status response)))
+        (is (= [] (get-in response [:body :items])))))))
+
+(deftest test-get-item
+  (testing "Getting existing item returns 200"
+    (with-redefs [db/get-item (fn [id]
+                                (when (= id 1)
+                                  {:id 1 :name "Test" :email "test@example.org"}))]
+      (let [request {:path-params {:id 1}}
+            response (handler/get-item request)]
+        (is (= 200 (:status response)))
+        (is (= {:id 1 :name "Test" :email "test@example.org"} (:body response))))))
+
+  (testing "Getting non-existent item returns 404"
+    (with-redefs [db/get-item (fn [_] nil)]
+      (let [request {:path-params {:id 999}}
+            response (handler/get-item request)]
+        (is (= 404 (:status response)))
+        (is (= {:error "Not Found"} (:body response)))))))
+
+(deftest test-create-item
+  (testing "Creating item with valid data returns 201"
+    (with-redefs [db/store-item! (fn [_name _email] 42)
+                  db/get-item (fn [id]
+                                (when (= id 42)
+                                  {:id 42 :name "New Item" :email "new@example.org"}))]
+      (let [request {:body-params {:name "New Item" :email "new@example.org"}}
+            response (handler/create-item request)]
+        (is (= 201 (:status response)))
+        (is (= "/item/42" (get-in response [:headers "Location"])))
+        (is (= {:id 42 :name "New Item" :email "new@example.org"} (:body response))))))
+
+  (testing "Created item has all expected fields"
+    (with-redefs [db/store-item! (fn [_name _email] 1)
+                  db/get-item (fn [id] {:id id :name "Test" :email "test@example.org"})]
+      (let [request {:body-params {:name "Test" :email "test@example.org"}}
+            response (handler/create-item request)]
+        (is (contains? (:body response) :id))
+        (is (contains? (:body response) :name))
+        (is (contains? (:body response) :email))))))
\ No newline at end of file
diff --git a/test/yohoho/helpers_test.clj b/test/yohoho/helpers_test.clj
new file mode 100644
index 0000000..4aae616
--- /dev/null
+++ b/test/yohoho/helpers_test.clj
@@ -0,0 +1,35 @@
+(ns yohoho.helpers-test
+  (:require [clojure.test :refer :all]
+            [yohoho.helpers :as helpers]))
+
+(deftest test-post-payload-content-type-json-middleware
+  (let [mock-handler (fn [_request] {:status 200 :body "Success"})
+        wrapped-handler (helpers/post-payload-content-type-json-middleware mock-handler)]
+
+    (testing "GET requests pass through without content-type check"
+      (let [request {:request-method :get}
+            response (wrapped-handler request)]
+        (is (= 200 (:status response)))
+        (is (= "Success" (:body response)))))
+
+    (testing "POST with application/json passes through"
+      (let [request {:request-method :post
+                     :headers {"content-type" "application/json"}}
+            response (wrapped-handler request)]
+        (is (= 200 (:status response)))
+        (is (= "Success" (:body response)))))
+
+    (testing "POST without content-type returns 415"
+      (let [request {:request-method :post
+                     :headers {}}
+            response (wrapped-handler request)]
+        (is (= 415 (:status response)))
+        (is (= "Unsupported Media Type" (get-in response [:body :error])))
+        (is (= "Content-Type must be application/json" (get-in response [:body :message])))))
+
+    (testing "POST with wrong content-type returns 415"
+      (let [request {:request-method :post
+                     :headers {"content-type" "application/xml"}}
+            response (wrapped-handler request)]
+        (is (= 415 (:status response)))
+        (is (= "Unsupported Media Type" (get-in response [:body :error])))))))
diff --git a/test/yohoho/integration_test.clj b/test/yohoho/integration_test.clj
new file mode 100644
index 0000000..05624b5
--- /dev/null
+++ b/test/yohoho/integration_test.clj
@@ -0,0 +1,196 @@
+(ns yohoho.integration-test
+  (:require [clojure.test :refer :all]
+            [yohoho.app :as app]
+            [yohoho.db :as db]
+            [next.jdbc :as jdbc]
+            [clojure.data.json :as json]))
+
+
+;; In-memory database setup ---------------------------------------
+(def schema-sql
+  "CREATE TABLE items (
+     id INTEGER PRIMARY KEY,
+     name TEXT NOT NULL,
+     email TEXT NOT NULL
+   );")
+
+(defn with-memory-db [f]
+  (let [conn (jdbc/get-connection
+              {:dbtype "sqlite"
+               :dbname ":memory:"})]
+    ;; create schema on the SAME connection
+    (jdbc/execute! conn [schema-sql])
+
+    ;; force db.clj to reuse this connection
+    (with-redefs [db/db conn]
+      (f))
+
+    (.close conn)))
+
+(use-fixtures :each with-memory-db)
+
+
+;; Helpers --------------------------------------------------------
+(defn parse-json-body [response]
+  (when-let [body (:body response)]
+    (cond
+      (string? body)
+      (json/read-str body :key-fn keyword)
+
+      (instance? java.io.InputStream body)
+      (json/read (java.io.InputStreamReader. body) :key-fn keyword)
+
+      :else
+      body)))
+
+(defn make-request
+  "Helper to make a request to the app"
+  [method uri & {:keys [body headers]}]
+  (let [request {:request-method method
+                 :uri uri
+                 :headers (merge {"content-type" "application/json"} headers)}
+        request (if body
+                  (assoc request :body-params body)
+                  request)]
+    (app/app request)))
+
+
+;; Tests ----------------------------------------------------------
+(deftest test-health-check
+  (testing "Health check endpoint returns 200"
+    (let [response (make-request :get "/ahoy")]
+      (is (= 200 (:status response)))
+      (is (string? (:body response))))))
+
+(deftest test-create-and-retrieve-item
+  (testing "Creating an item and retrieving it"
+    (let [item-data {:name "Integration Test Item" :email "integration@test.com"}
+          create-response (make-request :post "/items" :body item-data)]
+
+      ;; Verify creation response
+      (is (= 201 (:status create-response)))
+      (let [created-item (parse-json-body create-response)]
+        (is (number? (:id created-item)))
+        (is (= "Integration Test Item" (:name created-item)))
+        (is (= "integration@test.com" (:email created-item)))
+
+        ;; Verify Location header
+        (is (= (str "/item/" (:id created-item))
+               (get-in create-response [:headers "Location"])))
+
+        ;; Retrieve the item by ID
+        (let [get-response (make-request :get (str "/item/" (:id created-item)))
+              retrieved-item (parse-json-body get-response)]
+          (is (= 200 (:status get-response)))
+          (is (= created-item retrieved-item)))))))
+
+(deftest test-get-all-items
+  (testing "Getting all items returns empty list initially"
+    (let [response (make-request :get "/items")
+          body (parse-json-body response)]
+      (is (= 200 (:status response)))
+      (is (= [] (:items body)))))
+
+  (testing "Getting all items after creating some"
+    ;; Create multiple items
+    (make-request :post "/items" :body {:name "Item 1" :email "item1@test.com"})
+    (make-request :post "/items" :body {:name "Item 2" :email "item2@test.com"})
+    (make-request :post "/items" :body {:name "Item 3" :email "item3@test.com"})
+
+    (let [response (make-request :get "/items")
+          body (parse-json-body response)]
+      (is (= 200 (:status response)))
+      (is (= 3 (count (:items body))))
+      (is (every? #(contains? % :id) (:items body)))
+      (is (every? #(contains? % :name) (:items body)))
+      (is (every? #(contains? % :email) (:items body))))))
+
+(deftest test-get-nonexistent-item
+  (testing "Getting non-existent item returns 404"
+    (let [response (make-request :get "/item/999")
+          body (parse-json-body response)]
+      (is (= 404 (:status response)))
+      (is (= "Not Found" (:error body))))))
+
+(deftest test-create-item-validation
+  (testing "Creating item without email fails validation"
+    (let [response (make-request :post "/items" :body {:name "Test"})]
+      (is (= 400 (:status response)))))
+
+  (testing "Creating item without name fails validation"
+    (let [response (make-request :post "/items" :body {:email "test@example.com"})]
+      (is (= 400 (:status response)))))
+
+  (testing "Creating item with invalid email fails validation"
+    (let [response (make-request :post "/items" :body {:name "Test" :email "not-an-email"})]
+      (is (= 400 (:status response)))))
+
+  (testing "Creating item with empty payload fails validation"
+    (let [response (make-request :post "/items" :body {})]
+      (is (= 400 (:status response))))))
+
+(deftest test-content-type-validation
+  (testing "POST without content-type returns 415"
+    (let [response (make-request :post "/items" :body {:name "Test" :email "test@test.com"}
+                                 :headers {"content-type" nil})]
+      (is (= 415 (:status response)))))
+
+  (testing "POST with wrong content-type returns 415"
+    (let [response (make-request :post "/items" :body {:name "Test" :email "test@test.com"}
+                                 :headers {"content-type" "application/xml"})]
+      (is (= 415 (:status response))))))
+
+(deftest test-invalid-routes
+  (testing "Non-existent route returns 404"
+    (let [response (make-request :get "/nonexistent")]
+      (is (= 404 (:status response))))))
+
+(deftest test-openapi-endpoint
+  (testing "OpenAPI documentation is available"
+    (let [response (make-request :get "/openapi.json")]
+      (is (= 200 (:status response)))
+      (let [openapi-doc (parse-json-body response)]
+        (is (= "Yo-ho-ho API" (get-in openapi-doc [:info :title])))
+        (is (contains? openapi-doc :paths))))))
+
+(deftest test-item-id-coercion
+  (testing "Item ID path parameter is coerced to integer"
+    ;; Create an item first
+    (let [create-response (make-request :post "/items"
+                                        :body {:name "Test" :email "test@test.com"})
+          created-item (parse-json-body create-response)
+          item-id (:id created-item)]
+
+      ;; Request with string ID should work (coerced to int)
+      (let [response (make-request :get (str "/item/" item-id))]
+        (is (= 200 (:status response))))))
+
+  (testing "Invalid ID format returns 400"
+    (let [response (make-request :get "/item/not-a-number")]
+      (is (= 400 (:status response))))))
+
+(deftest test-multiple-items-workflow
+  (testing "Complete workflow: create multiple items, retrieve all, retrieve individual"
+    (let [items-to-create [{:name "Alice" :email "alice@example.com"}
+                           {:name "Bob" :email "bob@example.com"}
+                           {:name "Charlie" :email "charlie@example.com"}]
+          created-ids (atom [])]
+
+      ;; Create items
+      (doseq [item items-to-create]
+        (let [response (make-request :post "/items" :body item)
+              created (parse-json-body response)]
+          (is (= 201 (:status response)))
+          (swap! created-ids conj (:id created))))
+
+      ;; Verify all items in list
+      (let [list-response (make-request :get "/items")
+            all-items (:items (parse-json-body list-response))]
+        (is (= 3 (count all-items)))
+        (is (= #{"Alice" "Bob" "Charlie"} (set (map :name all-items)))))
+
+      ;; Verify each item individually
+      (doseq [id @created-ids]
+        (let [response (make-request :get (str "/item/" id))]
+          (is (= 200 (:status response)))
+          (is (= id (:id (parse-json-body response)))))))))
diff --git a/test/yohoho/schemas_test.clj b/test/yohoho/schemas_test.clj
new file mode 100644
index 0000000..a17095f
--- /dev/null
+++ b/test/yohoho/schemas_test.clj
@@ -0,0 +1,97 @@
+(ns yohoho.schemas-test
+  (:require [clojure.test :refer :all]
+            [yohoho.schemas :as s]
+            [malli.core :as m]))
+
+(deftest test-email-validation
+  (testing "Valid email addresses"
+    (is (m/validate s/Email "test@example.com"))
+    (is (m/validate s/Email "user.name@example.com"))
+    (is (m/validate s/Email "user+tag@example.co.uk"))
+    (is (m/validate s/Email "user_123@test-domain.com"))
+    (is (m/validate s/Email "a@b.c")))
+
+  (testing "Invalid email addresses"
+    (is (not (m/validate s/Email "notanemail")))
+    (is (not (m/validate s/Email "@example.com")))
+    (is (not (m/validate s/Email "user@")))
+    (is (not (m/validate s/Email "user @example.com")))
+    (is (not (m/validate s/Email "user@example")))
+    (is (not (m/validate s/Email "")))))
+
+(deftest test-item-input-schema
+  (testing "Valid item input"
+    (is (m/validate s/ItemInput {:name "Test Item" :email "test@example.com"}))
+    (is (m/validate s/ItemInput {:name "A" :email "a@b.c"})))
+
+  (testing "Invalid item input - missing fields"
+    (is (not (m/validate s/ItemInput {:name "Test"})))
+    (is (not (m/validate s/ItemInput {:email "test@example.com"})))
+    (is (not (m/validate s/ItemInput {}))))
+
+  (testing "Invalid item input - wrong types"
+    (is (not (m/validate s/ItemInput {:name 123 :email "test@example.com"})))
+    (is (not (m/validate s/ItemInput {:name "Test" :email "not-an-email"}))))
+
+  (testing "Extra fields are allowed (open map)"
+    (is (m/validate s/ItemInput {:name "Test" :email "test@example.com" :extra "field"}))))
+
+(deftest test-item-schema
+  (testing "Valid item"
+    (is (m/validate s/Item {:id 1 :name "Test" :email "test@example.com"}))
+    (is (m/validate s/Item {:id 999 :name "Long Name Here" :email "complex.email+tag@example.co.uk"})))
+
+  (testing "Invalid item - missing fields"
+    (is (not (m/validate s/Item {:id 1 :name "Test"})))
+    (is (not (m/validate s/Item {:id 1 :email "test@example.com"})))
+    (is (not (m/validate s/Item {:name "Test" :email "test@example.com"}))))
+
+  (testing "Invalid item - wrong types"
+    (is (not (m/validate s/Item {:id "not-a-number" :name "Test" :email "test@example.com"})))
+    (is (not (m/validate s/Item {:id 1.5 :name "Test" :email "test@example.com"})))
+    (is (not (m/validate s/Item {:id 1 :name "Test" :email "invalid-email"})))))
+
+(deftest test-items-response-schema
+  (testing "Valid items response"
+    (is (m/validate s/ItemsResponse {:items []}))
+    (is (m/validate s/ItemsResponse {:items [{:id 1 :name "Test" :email "test@example.com"}]}))
+    (is (m/validate s/ItemsResponse {:items [{:id 1 :name "Test1" :email "test1@example.com"}
+                                             {:id 2 :name "Test2" :email "test2@example.com"}]})))
+
+  (testing "Invalid items response - not a vector"
+    (is (not (m/validate s/ItemsResponse {:items {:id 1 :name "Test" :email "test@example.com"}})))
+    (is (not (m/validate s/ItemsResponse {:items "not-a-vector"}))))
+
+  (testing "Invalid items response - missing items key"
+    (is (not (m/validate s/ItemsResponse {})))
+    (is (not (m/validate s/ItemsResponse {:data []}))))
+
+  (testing "Invalid items response - invalid item in vector"
+    (is (not (m/validate s/ItemsResponse {:items [{:id 1 :name "Test"}]})))))
+
+(deftest test-error-response-schema
+  (testing "Valid error response with message"
+    (is (m/validate s/ErrorResponse {:error "Not Found" :message "Item does not exist"})))
+
+  (testing "Valid error response without message"
+    (is (m/validate s/ErrorResponse {:error "Not Found"})))
+
+  (testing "Invalid error response - missing error"
+    (is (not (m/validate s/ErrorResponse {:message "Something went wrong"})))
+    (is (not (m/validate s/ErrorResponse {}))))
+
+  (testing "Invalid error response - wrong types"
+    (is (not (m/validate s/ErrorResponse {:error 404 :message "Not Found"})))
+    (is (not (m/validate s/ErrorResponse {:error "Not Found" :message 123})))))
+
+(deftest test-error-400-response-schema
+  (testing "Valid 400 error response"
+    (is (m/validate s/Error400Response {:value {}
+                                        :type "reitit.coercion/request-coercion"
+                                        :coercion "malli"
+                                        :in ["request" "body-params"]
+                                        :humanized {:email ["should be a valid email"]}})))
+
+  (testing "Invalid 400 error - missing required fields"
+    (is (not (m/validate s/Error400Response {:value {}})))
+    (is (not (m/validate s/Error400Response {:type "type" :coercion "malli" :in [] :humanized {}})))))
\ No newline at end of file