Add unit tests for controller

grails/src/test/groovy/com/baeldung/grails/StudentControllerSpec.groovy

@@ -0,0 +1,82 @@
+package com.baeldung.grails
+
+import grails.testing.gorm.DomainUnitTest
+import grails.testing.web.controllers.ControllerUnitTest
+import spock.lang.*
+
+class StudentControllerSpec extends Specification implements ControllerUnitTest<StudentController>, DomainUnitTest<Student> {
+
+    void "Test the index action returns the correct model"() {
+        given:
+        controller.studentService = Mock(StudentService) {
+            list() >> [new Student(firstName: 'John',lastName: 'Doe')]
+        }
+
+        when:"The index action is executed"
+        controller.index()
+
+        then:"The model is correct"
+        model.studentList.size() == 1
+        model.studentList[0].firstName == 'John'
+        model.studentList[0].lastName == 'Doe'
+    }
+
+    void "Test the create action returns the correct model"() {
+        when:"The create action is executed"
+        controller.create()
+
+        then:"The model is correctly created"
+        model.student!= null
+    }
+
+
+    void "Test the show action with a null id"() {
+        given:
+        controller.studentService = Mock(StudentService) {
+            1 * get(null) >> null
+        }
+
+        when:"The show action is executed with a null domain"
+        controller.show(null)
+
+        then:"A 404 error is returned"
+        response.status == 404
+    }
+
+    void "Test the show action with a valid id"() {
+        given:
+        controller.studentService = Mock(StudentService) {
+            1 * get(2) >> new Student(firstName: 'John',lastName: 'Doe')
+        }
+
+        when:"A domain instance is passed to the show action"
+        controller.show(2)
+
+        then:"A model is populated containing the domain instance"
+        model.student instanceof Student
+        and:"And student is John Doe"
+        model.student.firstName == 'John'
+        model.student.lastName == 'Doe'
+    }
+
+    void "Test the delete action with an instance"() {
+        given:
+        controller.studentService = Mock(StudentService) {
+            1 * delete(2)
+        }
+
+        when:"The domain instance is passed to the delete action"
+        request.contentType = FORM_CONTENT_TYPE
+        request.method = 'DELETE'
+        controller.delete(2)
+
+        then:"The user is redirected to index"
+        response.redirectedUrl == '/student/index'
+    }
+}
+
+
+
+
+
+