import org.mockito.Mockito.`when`
import org.springframework.beans.factory.annotation.Autowired
import org.springframework.boot.context.properties.EnableConfigurationProperties
import org.springframework.boot.test.context.SpringBootTest
import org.junit.jupiter.api.Test

@ExtendWith(SpringExtension::class)
@EnableConfigurationProperties(value = [TokenConfiguration::class])
@ContextConfiguration(classes = [TokenService::class])
@SpringBootTest    
open class FooTest {
    
    @Autowired
    private lateinit var subject : TokenService

    @Autowired
    private lateinit var tokenConfiguration : TokenConfiguration

    @MockitoBean
    private lateinit var tokenGenerator : TokenGenerator
    
    @Test
    fun `generateToken with valid generate token request returns access token`() {
        val generateTokenRequest = GenerateTokenRequest(foo, bar)
        `when`(tokenGenerator.generateAccessToken(anyTokenPayLoad(generateTokenRequest))).thenReturn(accessToken)
        /* 
        We also tried a stub such as the following line but it gave us the same error

        `when`(tokenGenerator.generateAccessToken(any(TokenPayLoad::class.java))).thenReturn(accessToken) */
        val response = subject.generateToken(generateTokenRequest)
        assertThat(response).isNotNull
        assertThat(response.ttl).isEqualTo(ttl)
        assertThat(response.tokenType).isEqualTo(tokenType)
    }

    @Suppress("UNCHECKED_CAST")
    private fun <TokenPayLoad> anyTokenPayLoad(generateTokenRequest: GenerateTokenRequest): TokenPayLoad {
        return any() ?: TokenPayLoad(generateTokenRequest, tokenConfiguration) as TokenPayLoad
    }
}

import org.springframework.beans.factory.annotation.Value

@ConfigurationProperties
@RefreshScope
open class TokenConfiguration {

    @Value("Bearer")
    lateinit var tokenType: String

    @Value("3600L")
    var defaultTTL: Long = 0L
}

@Service
@EnableConfigurationProperties(value = [TokenConfiguration::class])
class TokenService
@Autowired
constructor(private var tokenGenerator: TokenGenerator,
            private var tokenConfiguration: TokenConfiguration) {
    fn generateToken(): GenerateTokenResponse{
        //some logic
        return generateTokenResponse 
    }             
}