diff --git a/di/src/test/java/org/panda_lang/utilities/inject/DependencyInjectionInstancesTest.java b/di/src/test/java/org/panda_lang/utilities/inject/DependencyInjectionInstancesTest.java
index 9659814..086c679 100644
--- a/di/src/test/java/org/panda_lang/utilities/inject/DependencyInjectionInstancesTest.java
+++ b/di/src/test/java/org/panda_lang/utilities/inject/DependencyInjectionInstancesTest.java
@@ -1,5 +1,6 @@
 package org.panda_lang.utilities.inject;
 
+import java.security.InvalidParameterException;
 import org.junit.jupiter.api.Test;
 
 import static org.junit.jupiter.api.Assertions.assertNotNull;
@@ -31,6 +32,7 @@ void shouldNotInjectInstances() {
             });
         });
 
+        assertThrows(InvalidParameterException.class, () -> injector.forConstructor(InvalidClass.class).newInstance(), "Class has contain one and only one constructor");
         assertThrows(DependencyInjectionException.class, () -> injector.newInstance(Service.class));
     }
 
@@ -46,4 +48,15 @@ public Service(Bean bean, Custom custom) {
         }
     }
 
+    private static class InvalidClass { // 2 constructors (only 1 is allowed)
+        public InvalidClass(Bean bean, Custom custom) {
+            assertNotNull(bean);
+            assertNotNull(custom);
+        }
+
+        public InvalidClass(Bean bean) {
+            assertNotNull(bean);
+        }
+    }
+
 }
diff --git a/di/src/test/java/org/panda_lang/utilities/inject/MethodsInvocationTest.java b/di/src/test/java/org/panda_lang/utilities/inject/MethodsInvocationTest.java
new file mode 100644
index 0000000..610fa66
--- /dev/null
+++ b/di/src/test/java/org/panda_lang/utilities/inject/MethodsInvocationTest.java
@@ -0,0 +1,72 @@
+package org.panda_lang.utilities.inject;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+public class MethodsInvocationTest {
+
+    private static class TestClass {
+
+        private String testString;
+        private int testInt = 0;
+
+        public void testMethod() {
+            this.testString = "test";
+        }
+
+        @TestAnnotation
+        public void annotatedMethod() {
+            this.testInt += 2;
+        }
+
+        @TestAnnotation
+        public void annotatedMethod(int value) {
+            this.testInt *= value;
+        }
+
+        @TestAnnotation2
+        public void annotatedMethod2() {
+            throw new IllegalStateException("This method should not be invoked");
+        }
+
+        public void failMethod() {
+            throw new RuntimeException();
+        }
+
+    }
+
+    @Retention(RetentionPolicy.RUNTIME)
+    private @interface TestAnnotation { }
+
+    @Retention(RetentionPolicy.RUNTIME)
+    private @interface TestAnnotation2 {}
+
+    @Test
+    void shouldInvokeMethods() throws NoSuchMethodException {
+        Injector injector = DependencyInjection.createInjector(resources -> {
+            resources.on(int.class).assignInstance(3);
+        });
+
+        TestClass testClass = new TestClass();
+        injector.invokeMethod(TestClass.class.getMethod("testMethod"), testClass);
+        assertEquals("test", testClass.testString);
+
+        injector.invokeAnnotatedMethods(TestAnnotation.class, testClass);
+        assertEquals(6, testClass.testInt);
+    }
+
+    @Test
+    void shouldNotInvokeMethods() throws NoSuchMethodException {
+        Injector injector = DependencyInjection.createInjector(resources -> {
+            resources.on(int.class).assignInstance(3);
+        });
+
+        TestClass testClass = new TestClass();
+        assertThrows(DependencyInjectionException.class, () -> injector.invokeMethod(TestClass.class.getMethod("failMethod"), testClass));
+    }
+
+}