BAEL-2650 - Kotlin standard functions: run, with, let, also and apply (#6553)
This commit is contained in:
parent
0746c25c7f
commit
10e9cbda1e
|
@ -0,0 +1,25 @@
|
|||
package com.baeldung.scope
|
||||
|
||||
data class Student(var studentId: String = "", var name: String = "", var surname: String = "") {
|
||||
}
|
||||
|
||||
data class Teacher(var teacherId: Int = 0, var name: String = "", var surname: String = "") {
|
||||
fun setId(anId: Int): Teacher = apply { teacherId = anId }
|
||||
fun setName(aName: String): Teacher = apply { name = aName }
|
||||
fun setSurname(aSurname: String): Teacher = apply { surname = aSurname }
|
||||
}
|
||||
|
||||
data class Headers(val headerInfo: String)
|
||||
|
||||
data class Response(val headers: Headers)
|
||||
|
||||
data class RestClient(val url: String) {
|
||||
fun getResponse() = Response(Headers("some header info"))
|
||||
}
|
||||
|
||||
data class BankAccount(val id: Int) {
|
||||
fun checkAuthorization(username: String) = Unit
|
||||
fun addPayee(payee: String) = Unit
|
||||
fun makePayment(paymentDetails: String) = Unit
|
||||
|
||||
}
|
|
@ -0,0 +1,119 @@
|
|||
package com.baeldung.scope
|
||||
|
||||
import org.assertj.core.api.Assertions.assertThat
|
||||
import org.junit.Test
|
||||
|
||||
class ScopeFunctionsUnitTest {
|
||||
|
||||
class Logger {
|
||||
|
||||
var called : Boolean = false
|
||||
|
||||
fun info(message: String) {
|
||||
called = true
|
||||
}
|
||||
|
||||
fun wasCalled() = called
|
||||
}
|
||||
|
||||
@Test
|
||||
fun shouldTransformWhenLetFunctionUsed() {
|
||||
val stringBuider = StringBuilder()
|
||||
val numberOfCharacters = stringBuider.let {
|
||||
it.append("This is a transformation function.")
|
||||
it.append("It takes a StringBuilder instance and returns the number of characters in the generated String")
|
||||
it.length
|
||||
}
|
||||
assertThat(numberOfCharacters).isEqualTo(128)
|
||||
}
|
||||
|
||||
@Test
|
||||
fun shouldHandleNullabilityWhenLetFunctionUsed() {
|
||||
|
||||
val message: String? = "hello there!"
|
||||
val charactersInMessage = message?.let {
|
||||
"At this point is safe to reference the variable. Let's print the message: $it"
|
||||
} ?: "default value"
|
||||
|
||||
assertThat(charactersInMessage).isEqualTo("At this point is safe to reference the variable. Let's print the message: hello there!")
|
||||
|
||||
val aNullMessage = null
|
||||
val thisIsNull = aNullMessage?.let {
|
||||
"At this point it would be safe to reference the variable. But it will not really happen because it is null. Let's reference: $it"
|
||||
} ?: "default value"
|
||||
|
||||
assertThat(thisIsNull).isEqualTo("default value")
|
||||
}
|
||||
|
||||
@Test
|
||||
fun shouldInitializeObjectWhenUsingApply() {
|
||||
val aStudent = Student().apply {
|
||||
studentId = "1234567"
|
||||
name = "Mary"
|
||||
surname = "Smith"
|
||||
}
|
||||
assertThat(aStudent.name).isEqualTo("Mary")
|
||||
}
|
||||
|
||||
@Test
|
||||
fun shouldAllowBuilderStyleObjectDesignWhenApplyUsedInClassMethods() {
|
||||
val teacher = Teacher()
|
||||
.setId(1000)
|
||||
.setName("Martha")
|
||||
.setSurname("Spector")
|
||||
|
||||
assertThat(teacher.surname).isEqualTo("Spector")
|
||||
}
|
||||
|
||||
@Test
|
||||
fun shouldAllowSideEffectWhenUsingAlso() {
|
||||
val restClient = RestClient("http://www.someurl.com")
|
||||
|
||||
val logger = Logger()
|
||||
|
||||
val headers = restClient
|
||||
.getResponse()
|
||||
.also { logger.info(it.toString()) }
|
||||
.headers
|
||||
|
||||
assertThat(logger.wasCalled()).isTrue()
|
||||
assertThat(headers.headerInfo).isEqualTo("some header info")
|
||||
}
|
||||
|
||||
@Test
|
||||
fun shouldInitializeFieldWhenAlsoUsed() {
|
||||
val aStudent = Student().also { it.name = "John"}
|
||||
assertThat(aStudent.name).isEqualTo("John")
|
||||
}
|
||||
|
||||
@Test
|
||||
fun shouldLogicallyGroupObjectCallsWhenUsingWith() {
|
||||
val bankAccount = BankAccount(1000)
|
||||
with (bankAccount) {
|
||||
checkAuthorization("someone")
|
||||
addPayee("some payee")
|
||||
makePayment("payment information")
|
||||
}
|
||||
}
|
||||
|
||||
@Test
|
||||
fun shouldConvertObjectWhenRunUsed() {
|
||||
val stringBuider = StringBuilder()
|
||||
val numberOfCharacters = stringBuider.run {
|
||||
append("This is a transformation function.")
|
||||
append("It takes a StringBuilder instance and returns the number of characters in the generated String")
|
||||
length
|
||||
}
|
||||
assertThat(numberOfCharacters).isEqualTo(128)
|
||||
}
|
||||
|
||||
@Test
|
||||
fun shouldHandleNullabilityWhenRunIsUsed() {
|
||||
val message: String? = "hello there!"
|
||||
val charactersInMessage = message?.run {
|
||||
"At this point is safe to reference the variable. Let's print the message: $this"
|
||||
} ?: "default value"
|
||||
assertThat(charactersInMessage).isEqualTo("At this point is safe to reference the variable. Let's print the message: hello there!")
|
||||
}
|
||||
|
||||
}
|
Loading…
Reference in New Issue