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Fix SimpleMailMessage nullability annotations
Fixes the nullability annotations in `SimpleMailMessage` so the `set*(...)` methods have their parameters marked as `@Nullable`. These method parameters had no annotations and when `SimpleMailMessage` is used from Kotlin with `-Xjsr305=strict` enabled, the `set*(...)` methods were treated as being marked `@NonNull`. This also meant Kotlin would not see matched pairs of get/set methods as `var` properties, so calling `message.text = "Text"` would not compile in Kotlin. Adds tests in `SimpleMailMessageJsr305ComplianceTests.kt` that verify the nullability annotations for `SimpleMailMessage` are correct. This file will actually fail to compile if the nullability annotations are missing, causing the tests to fail. Also modifies `spring-context-support.gradle` to force the Kotlin test code to compile with `-Xjsr305=strict`, enabling the test code to work properly.
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...upport/src/test/kotlin/org/springframework/mail/SimpleMailMessageJsr305ComplianceTests.kt
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| Original file line number | Diff line number | Diff line change |
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| package org.springframework.mail/* | ||
| * Copyright 2002-2022 the original author or authors. | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * https://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
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|
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| import org.junit.jupiter.api.Test | ||
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| import java.util.* | ||
| import kotlin.reflect.KParameter | ||
| import kotlin.reflect.full.declaredMemberFunctions | ||
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| /** | ||
| * These tests are intended to verify correct behavior of SimpleMailMessage when used from | ||
| * Kotlin with `-Xjsr305=strict` enabled to strictly enforce Java nullability annotations. | ||
| * | ||
| * Kotlin's JSR305 strict mode treats all non-annotated parameters and return types as | ||
| * non-nullable, while Java code does not perform any such checks and can still pass and | ||
| * capture null parameters and return values, respectively. | ||
| * | ||
| * Kotlin also treats null and definitely-non-null types as incompatible types. As such, | ||
| * The get/set methods in [SimpleMailMessage] must therefore have coherent nullability | ||
| * annotations for Kotlin to treat them as properties with getters and setters. Otherwise, | ||
| * Kotlin sees them as functions with incompatible get/set types and does not associate | ||
| * them. | ||
| * | ||
| * These errors often appear only at compile time and not in the IDE, making it somewhat | ||
| * confusing to troubleshoot. | ||
| * | ||
| * __If any of the annotations on [SimpleMailMessage] are missing or incoherent with their | ||
| * respective getter / setter method, this test will actually fail to compile, which is | ||
| * a form of test failure in and of itself.__ | ||
| * | ||
| * @author Steve Gerhardt | ||
| */ | ||
| class SimpleMailMessageJsr305ComplianceTests { | ||
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| private inline fun <reified T : Any> T.getUnsafeVarargSetterByReflection(name : String) : Function1<Array<Any?>?, Unit> { | ||
| return { arrayForVararg -> | ||
| this::class.declaredMemberFunctions | ||
| .first { | ||
| val isFirstValueParameterVararg = it.parameters | ||
| .firstOrNull { p -> p.kind == KParameter.Kind.VALUE } | ||
| ?.isVararg == true | ||
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| it.name == name && isFirstValueParameterVararg | ||
| } | ||
| .call(this, arrayForVararg) | ||
| } | ||
| } | ||
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| @Test | ||
| fun `Null message parameters via Java setters should be null via Kotlin getters`() { | ||
| val message = SimpleMailMessage() | ||
| message.setFrom(null) | ||
| message.getUnsafeVarargSetterByReflection("setTo")(null) | ||
| message.setReplyTo(null) | ||
| message.getUnsafeVarargSetterByReflection("setCc")(null) | ||
| message.getUnsafeVarargSetterByReflection("setBcc")(null) | ||
| message.setSentDate(null) | ||
| message.setSubject(null) | ||
| message.setText(null) | ||
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| assert(message.from == null) | ||
| assert(message.to == null) | ||
| assert(message.replyTo == null) | ||
| assert(message.cc == null) | ||
| assert(message.bcc == null) | ||
| assert(message.sentDate == null) | ||
| assert(message.subject == null) | ||
| assert(message.text == null) | ||
| } | ||
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| @Test | ||
| fun `To, CC, and BCC with lists of null recipients should appear as valid lists with null entries via Kotlin getters`() { | ||
| val message = SimpleMailMessage() | ||
| message.setTo(*arrayOf(null, null, null, null)) | ||
| message.setCc(*arrayOf(null, null, null)) | ||
| message.setBcc(*arrayOf(null, null)) | ||
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| assert(message.to.let { it != null && it.size == 4 && it.all { item -> item == null } }) | ||
| assert(message.cc.let { it != null && it.size == 3 && it.all { item -> item == null } }) | ||
| assert(message.bcc.let { it != null && it.size == 2 && it.all { item -> item == null } }) | ||
| } | ||
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| @Test | ||
| fun `Non-null message parameters via Java setters should be non-null via Kotlin getters`() { | ||
| val message = SimpleMailMessage() | ||
| message.setFrom("me@mail.org") | ||
| message.setTo("you@mail.org") | ||
| message.setReplyTo("reply@mail.org") | ||
| message.setCc(*arrayOf("he@mail.org", "she@mail.org")) | ||
| message.setBcc(*arrayOf("us@mail.org", "them@mail.org")) | ||
| val sentDate = Date() | ||
| message.setSentDate(sentDate) | ||
| message.setSubject("my subject") | ||
| message.setText("my text") | ||
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| assert(message.from == "me@mail.org") | ||
| assert(message.to.let { it != null && it.contains("you@mail.org") }) | ||
| assert(message.replyTo == "reply@mail.org") | ||
| assert(message.cc.let { it != null && it.toList() == listOf("he@mail.org", "she@mail.org") }) | ||
| assert(message.bcc.let { it != null && it.toList() == listOf("us@mail.org", "them@mail.org") }) | ||
| assert(message.sentDate == sentDate) | ||
| assert(message.subject == "my subject") | ||
| assert(message.text == "my text") | ||
| } | ||
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| @Test | ||
| fun `Message parameters can be set via Kotlin setters`() { | ||
| val message = SimpleMailMessage() | ||
| message.from = "me@mail.org" | ||
| message.replyTo = "reply@mail.org" | ||
| val sentDate = Date() | ||
| message.sentDate = sentDate | ||
| message.subject = "my subject" | ||
| message.text = "my text" | ||
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| assert(message.from == "me@mail.org") | ||
| assert(message.replyTo == "reply@mail.org") | ||
| assert(message.sentDate == sentDate) | ||
| assert(message.subject == "my subject") | ||
| assert(message.text == "my text") | ||
| } | ||
| } |