Additional tests for copy in Optics

arrow-libs/optics/arrow-optics-ksp-plugin/src/test/kotlin/arrow/optics/plugin/CopyTest.kt

@@ -0,0 +1,99 @@
+package arrow.optics.plugin
+
+import org.junit.jupiter.api.Test
+
+// from https://kotlinlang.slack.com/archives/C5UPMM0A0/p1688822411819599
+// and https://github.com/overfullstack/my-lab/blob/master/arrow/src/test/kotlin/ga/overfullstack/optics/OpticsLab.kt
+
+val copyCode = """
+@optics data class Person(val name: String, val age: Int, val address: Address) {
+  companion object
+}
+@optics data class Address(val street: Street, val city: City, val coordinates: List<Int>) {
+  companion object
+}
+@optics data class Street(val name: String, val number: Int?) {
+  companion object
+}
+@optics data class City(val name: String, val country: String) {
+  companion object
+}
+
+fun Person.moveToAmsterdamCopy(): Person = copy {
+  Person.address.city.name set "Amsterdam"
+  Person.address.city.country set "Netherlands"
+  Person.address .coordinates set listOf(2, 3)
+}
+
+fun Person.moveToAmsterdamInside(): Person = copy {
+  inside(Person.address.city) {
+    City.name set "Amsterdam"
+    City.country set "Netherlands"
+  }
+}
+
+val me =
+  Person(
+    "Gopal",
+    99,
+    Address(Street("Kotlinstraat", 1), City("Hilversum", "Netherlands"), listOf(1, 2))
+  )
+"""
+
+class CopyTest {
+  @Test
+  fun `code compiles`() {
+    """
+      |package PersonTest
+      |$imports
+      |$copyCode
+      """.compilationSucceeds()
+  }
+
+  @Test
+  fun `birthday increments`() {
+    """
+      |package PersonTest
+      |$imports
+      |$copyCode
+      |val meAfterBirthdayParty = Person.age.modify(me) { it + 1 }
+      |val r = Person.age.get(meAfterBirthdayParty)
+      """.evals("r" to 100)
+  }
+
+  @Test
+  fun `moving to another city`() {
+    """
+      |package PersonTest
+      |$imports
+      |$copyCode
+      |val newAddress =
+      |  Address(Street("Kotlinplein", null), City("Amsterdam", "Netherlands"), listOf(1, 2))
+      |val meAfterMoving = Person.address.set(me, newAddress)
+      |val r = Person.address.get(meAfterMoving).street.name
+      """.evals("r" to "Kotlinplein")
+  }
+
+  @Test
+  fun `optics composition`() {
+    """
+      |package PersonTest
+      |$imports
+      |$copyCode
+      |val personCity: Lens<Person, String> = Person.address compose Address.city compose City.name
+      |val meAtTheCapital = personCity.set(me, "Amsterdam")
+      |val r = meAtTheCapital.address.city.name
+      """.evals("r" to "Amsterdam")
+  }
+
+  @Test
+  fun `optics copy to modify multiple fields`() {
+    """
+      |package PersonTest
+      |$imports
+      |$copyCode
+      |val meAfterMoving = me.moveToAmsterdamInside()
+      |val r = meAfterMoving.address.city.name
+      """.evals("r" to "Amsterdam")
+  }
+}

arrow-libs/optics/arrow-optics/src/commonTest/kotlin/arrow/optics/CopyTest.kt

@@ -0,0 +1,111 @@
+package arrow.optics
+
+import io.kotest.core.spec.style.StringSpec
+import io.kotest.matchers.shouldBe
+
+// from https://kotlinlang.slack.com/archives/C5UPMM0A0/p1688822411819599
+// and https://github.com/overfullstack/my-lab/blob/master/arrow/src/test/kotlin/ga/overfullstack/optics/OpticsLab.kt
+
+data class Person(val name: String, val age: Int, val address: Address) {
+  companion object {
+    val name: Lens<Person, String> = Lens(
+      get = { it.name },
+      set = { p, x -> p.copy(name = x) }
+    )
+    val age: Lens<Person, Int> = Lens(
+      get = { it.age },
+      set = { p, x -> p.copy(age = x) }
+    )
+    val address: Lens<Person, Address> = Lens(
+      get = { it.address },
+      set = { p, x -> p.copy(address = x) }
+    )
+  }
+}
+data class Address(val street: Street, val city: City, val coordinates: List<Int>) {
+  companion object {
+    val city: Lens<Address, City> = Lens(
+      get = { it.city },
+      set = { a, x -> a.copy(city = x) }
+    )
+    val coordinates: Lens<Address, List<Int>> = Lens(
+      get = { it.coordinates },
+      set = { a, x -> a.copy(coordinates = x) }
+    )
+  }
+}
+data class Street(val name: String, val number: Int?)
+data class City(val name: String, val country: String) {
+  companion object {
+    val name: Lens<City, String> = Lens(
+      get = { it.name },
+      set = { c, x -> c.copy(name = x) }
+    )
+    val country: Lens<City, String> = Lens(
+      get = { it.country },
+      set = { c, x -> c.copy(country = x) }
+    )
+  }
+}
+
+fun Person.moveToAmsterdamCopy(): Person = copy {
+  Person.address + Address.city + City.name set "Amsterdam"
+  Person.address + Address.city + City.country set "Netherlands"
+  Person.address + Address.coordinates set listOf(2, 3)
+}
+
+fun Person.moveToAmsterdamInside(): Person = copy {
+  inside(Person.address + Address.city) {
+    City.name set "Amsterdam"
+    City.country set "Netherlands"
+  }
+}
+
+class CopyTest : StringSpec({
+  "optics" {
+    val me =
+      Person(
+        "Gopal",
+        99,
+        Address(Street("Kotlinstraat", 1), City("Hilversum", "Netherlands"), listOf(1, 2))
+      )
+
+    Person.name.get(me) shouldBe "Gopal"
+
+    val meAfterBirthdayParty = Person.age.modify(me) { it + 1 }
+    Person.age.get(meAfterBirthdayParty) shouldBe 100
+
+    val newAddress =
+      Address(Street("Kotlinplein", null), City("Amsterdam", "Netherlands"), listOf(1, 2))
+    val meAfterMoving = Person.address.set(me, newAddress)
+    Person.address.get(meAfterMoving) shouldBe newAddress
+  }
+
+  "optics composition" {
+    val personCity: Lens<Person, String> = Person.address compose Address.city compose City.name
+
+    val me =
+      Person(
+        "Alejandro",
+        35,
+        Address(Street("Kotlinstraat", 1), City("Hilversum", "Netherlands"), listOf(1, 2))
+      )
+
+    personCity.get(me) shouldBe "Hilversum"
+    val meAtTheCapital = personCity.set(me, "Amsterdam")
+    meAtTheCapital.address.city.name shouldBe "Amsterdam"
+  }
+
+  "optics copy to modify multiple fields" {
+    val me =
+      Person(
+        "Alejandro",
+        35,
+        Address(Street("Kotlinstraat", 1), City("Hilversum", "Netherlands"), listOf(1, 2))
+      )
+    val meAfterMoving1 = me.moveToAmsterdamInside()
+    val meAfterMoving2 = me.moveToAmsterdamInside()
+    meAfterMoving1 shouldBe meAfterMoving2
+    meAfterMoving1.address.city.name shouldBe "Amsterdam"
+  }
+})