From df27b194f4f02906a87a538f7f2d69a6e387045a Mon Sep 17 00:00:00 2001
From: KUNAL KUMAR <kunaldevspro@gmail.com>
Date: Sat, 3 Jan 2026 19:04:01 +0530
Subject: [PATCH] test: added test coverage for AddUser func

---
 internal/users/users.go      | 44 ++++++++++++++++++
 internal/users/users_test.go | 90 ++++++++++++++++++++++++++++++++++++
 2 files changed, 134 insertions(+)
 create mode 100644 internal/users/users.go
 create mode 100644 internal/users/users_test.go

diff --git a/internal/users/users.go b/internal/users/users.go
new file mode 100644
index 0000000..f5bfb2e
--- /dev/null
+++ b/internal/users/users.go
@@ -0,0 +1,44 @@
+package users
+
+import (
+	"fmt"
+	"net/mail"
+)
+
+type User struct {
+	FirstName string
+	LastName  string
+	Email     mail.Address
+}
+
+type Manager struct {
+	users []User
+}
+
+func NewManager() *Manager {
+	return &Manager{}
+}
+
+func (m *Manager) AddUser(firstName string, lastName string, email string) error {
+	if firstName == "" {
+		return fmt.Errorf("invalid first name: %q", firstName)
+	}
+	if lastName == "" {
+		return fmt.Errorf("invalid last name:%q", lastName)
+	}
+
+	parsedAddress, err := mail.ParseAddress(email)
+	if err != nil {
+		return fmt.Errorf("invalid email: %s", email)
+	}
+
+	newUser := User{
+		FirstName: firstName,
+		LastName:  lastName,
+		Email:     *parsedAddress,
+	}
+
+	m.users = append(m.users, newUser)
+
+	return nil
+}
diff --git a/internal/users/users_test.go b/internal/users/users_test.go
new file mode 100644
index 0000000..74d8a94
--- /dev/null
+++ b/internal/users/users_test.go
@@ -0,0 +1,90 @@
+package users
+
+import (
+	"errors"
+	"net/mail"
+	"reflect"
+	"testing"
+)
+
+func TestAddUser(t *testing.T) {
+	testManager := NewManager()
+
+	testFirstName := "jhon"
+	testLastName := "smith"
+	testEmail, err := mail.ParseAddress("foo@bar.com")
+	if err != nil {
+		t.Fatalf("failed to parse email: %v", err)
+	}
+
+	err = testManager.AddUser(testFirstName, testLastName, testEmail.Address)
+	if err != nil {
+		t.Fatalf("failed to add user: %v", err)
+	}
+
+	if len(testManager.users) != 1 {
+		t.Fatalf("failed to add user: expected 1 user, got %v", len(testManager.users))
+		if len(testManager.users) < 1 {
+			t.Fatal()
+		}
+	}
+
+	expectedUser := User{
+		FirstName: testFirstName,
+		LastName:  testLastName,
+		Email:     *testEmail,
+	}
+
+	founduser := testManager.users[0]
+	if !reflect.DeepEqual(expectedUser, founduser) {
+		t.Fatalf("failed to add user: expected %v, got %v",
+			expectedUser, founduser)
+	}
+}
+
+func TestAddUserInvalidEmail(t *testing.T) {
+	testManager := NewManager()
+
+	testFirstName := "jhon"
+	testLastName := "smith"
+	testEmail := "foobar"
+
+	err := testManager.AddUser(testFirstName, testLastName, testEmail)
+	if err == nil {
+		t.Errorf("no error returned when adding invalid email")
+	} else {
+		expectedErr := errors.New("invalid email: foobar")
+		if err.Error() != expectedErr.Error() {
+			t.Errorf("error mismatch: expected %v, got %v", expectedErr, err)
+		}
+	}
+
+	if len(testManager.users) > 0 {
+		t.Fatalf("bad test manager count: expected 1 user, got %v", len(testManager.users))
+	}
+}
+
+func TestAddUserFirstName(t *testing.T) {
+	testManager := NewManager()
+
+	testFirstName := ""
+	testLastName := "smith"
+	testEmail, err := mail.ParseAddress("foo@bar.com")
+	if err != nil {
+		t.Errorf("no error returned when adding invalid email %v", err)
+	}
+
+	err = testManager.AddUser(testFirstName, testLastName, testEmail.String())
+	if err == nil {
+		t.Errorf("no error returned or invalid email")
+	} else {
+		expectedErr := "invalid first name: \"\""
+		if err.Error() != expectedErr {
+			t.Errorf("error mismatch: expected %v, got %v", expectedErr, err)
+		}
+	}
+
+	if len(testManager.users) > 0 {
+		t.Fatalf("bad test manager count: expected 1 user, got %v", len(testManager.users))
+	}
+}