Fix failure in UserRouteTest

app/src/test/kotlin/com/wbrawner/twigs/server/api/ApiTest.kt

@@ -12,6 +12,7 @@ import io.ktor.client.*
 import io.ktor.client.plugins.contentnegotiation.*
 import io.ktor.serialization.kotlinx.json.*
 import io.ktor.server.testing.*
+import kotlinx.serialization.json.Json
 import org.junit.jupiter.api.BeforeEach
 
 open class ApiTest {
@@ -70,7 +71,10 @@ open class ApiTest {
         }
         val client = createClient {
             install(ContentNegotiation) {
-                json()
+                json(json = Json {
+                    encodeDefaults = true
+                    explicitNulls = false
+                })
             }
         }
         test(client)

app/src/test/kotlin/com/wbrawner/twigs/server/api/UserRouteTest.kt

@@ -77,7 +77,7 @@ class UserRouteTest : ApiTest() {
 
     @Test
     fun `login with valid email and password returns 200`() = apiTest { client ->
-        val request = LoginRequest(TEST_USER.email, TEST_USER.password)
+        val request = LoginRequest(requireNotNull(TEST_USER.email), TEST_USER.password)
         val response = client.post("/api/users/login") {
             header("Content-Type", "application/json")
             setBody(request)
@@ -172,14 +172,14 @@ class UserRouteTest : ApiTest() {
         val userResponse = response.body<UserResponse>()
         assert(userResponse.id.isNotBlank())
         assertEquals(request.username, userResponse.username)
-        assertEquals("", userResponse.email)
+        assertEquals(null, userResponse.email)
         assertEquals(initialUserCount + 1, userRepository.entities.size)
         val savedUser: User? = userRepository.findAll("newuser").firstOrNull()
         assertNotNull(savedUser)
         requireNotNull(savedUser)
         assertEquals(userResponse.id, savedUser.id)
         assertEquals(request.username, savedUser.name)
-        assertEquals("", savedUser.email)
+        assertEquals(null, savedUser.email)
         assertEquals("newpass", savedUser.password)
     }