Closes #1: Should not reinitialize Resources if already initialized

README.md

@@ -20,13 +20,15 @@ Declare a `Resources` in one of the three following ways, and register `Server`
 
 Get a `Resources` from:
 1. A test method parameter injection, or
-2. An instance variable, or
-3. A static variable.
+2. An instance field, or
+3. A static field.
 
 The difference is in the lifecycle of the `Resources` object. For `#1`, a new instance is created for every test method. 
 `#2` is the same as `#1` unless the test class declares `@TestInstance(TestInstance.Lifecycle.PER_CLASS)`, in which case 
 one instance is shared among all the tests. `#3` is obviously one instance shared among all the tests.
 
+Note that for `#2` and `#3`, if the variable is already been assigned a value by the user, the extension will not 
+reinitialize it.
 
 ```
 @ExtendWith(GrpcCleanupExtension.class)

gradle.properties

@@ -10,7 +10,7 @@ ktlintVersion=9.3.0
 bintrayPluginVersion=1.8.5
 
 projectGroup=com.asarkar.grpc
-projectVersion=1.0.0
+projectVersion=1.0.1
 projectDescription=JUnit5 Extension that can automatically release gRPC resources at the end of the test
 licenseName=Apache-2.0
 licenseUrl=http://www.apache.org/licenses/LICENSE-2.0.txt

src/main/kotlin/com/asarkar/grpc/test/GrpcCleanupExtension.kt

@@ -40,6 +40,11 @@ class GrpcCleanupExtension :
         }
 
         if (shouldAccessResourcesField(ctx)) {
+            if (tryGet(ctx.requiredTestInstance) != null) {
+                throw PreconditionViolationException(
+                    "Either set lifecycle PER_CLASS or don't initialize Resources field"
+                )
+            }
             trySet(ctx.requiredTestInstance)
         }
     }
@@ -58,6 +63,7 @@ class GrpcCleanupExtension :
                     if (!successful) throw PostconditionViolationException("$resources and $it couldn't be released")
                     else throw PostconditionViolationException("$it couldn't be released")
                 }
+                trySet(ctx.requiredTestInstance, null)
             }
         }
         if (!successful) throw PostconditionViolationException("$resources couldn't be released")
@@ -81,7 +87,9 @@ class GrpcCleanupExtension :
                 throw JUnitException("Illegal state: Cannot access Resources field", e)
             }
             resourcesField = field
-            trySet(ctx.testInstance.orElse(null))
+            if (tryGet(ctx.testInstance.orElse(null)) == null) {
+                trySet(ctx.testInstance.orElse(null))
+            }
         }
     }
 
@@ -98,9 +106,9 @@ class GrpcCleanupExtension :
             !resourcesField.isStatic()
     }
 
-    private fun trySet(target: Any?) {
+    private fun trySet(target: Any?, value: Resources? = Resources()) {
         try {
-            resourcesField?.takeIf { target != null || it.isStatic() }?.set(target, Resources())
+            resourcesField?.takeIf { target != null || it.isStatic() }?.set(target, value)
         } catch (e: ReflectiveOperationException) {
             throw JUnitException("Illegal state: Cannot set Resources field", e)
         }

src/test/kotlin/com/asarkar/grpc/test/ExampleTestCase2.kt

@@ -6,7 +6,7 @@ import org.mockito.Mockito
 
 @ExtendWith(GrpcCleanupExtension::class)
 class ExampleTestCase2 {
-    private var resources: Resources? = null
+    private lateinit var resources: Resources
     private val setOfResources: Set<Resources?> = mutableSetOf()
     private val set = Mockito.spy(setOfResources)
 

src/test/kotlin/com/asarkar/grpc/test/ExampleTestCase3.kt

@@ -21,9 +21,4 @@ class ExampleTestCase3 {
     fun test2() {
         setOfResources.plus(resources)
     }
-
-    @Test
-    fun test3() {
-        setOfResources.plus(resources)
-    }
 }

src/test/kotlin/com/asarkar/grpc/test/ExampleTestCase7.kt

@@ -0,0 +1,24 @@
+package com.asarkar.grpc.test
+
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.TestInstance
+import org.junit.jupiter.api.extension.ExtendWith
+import org.mockito.Mockito
+
+@ExtendWith(GrpcCleanupExtension::class)
+@TestInstance(TestInstance.Lifecycle.PER_CLASS)
+class ExampleTestCase7 {
+    private var resources = Resources()
+    private val setOfResources: Set<Resources?> = mutableSetOf()
+    private val set = Mockito.spy(setOfResources)
+
+    @Test
+    fun test1() {
+        setOfResources.plus(resources)
+    }
+
+    @Test
+    fun test2() {
+        setOfResources.plus(resources)
+    }
+}

src/test/kotlin/com/asarkar/grpc/test/ExampleTestCase8.kt

@@ -0,0 +1,13 @@
+package com.asarkar.grpc.test
+
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.extension.ExtendWith
+
+@ExtendWith(GrpcCleanupExtension::class)
+class ExampleTestCase8 {
+    private var resources = Resources()
+
+    @Test
+    fun test() {
+    }
+}

src/test/kotlin/com/asarkar/grpc/test/GrpcCleanupExtensionIntegrationTests.kt

@@ -187,7 +187,7 @@ class GrpcCleanupExtensionIntegrationTests {
             .testEvents()
             .assertThatEvents()
             .haveExactly(
-                3,
+                2,
                 event(finishedSuccessfully())
             )
 
@@ -269,4 +269,40 @@ class GrpcCleanupExtensionIntegrationTests {
                 event(finishedWithFailure(instanceOf(PreconditionViolationException::class.java)))
             )
     }
+
+    @Test
+    fun testAlreadyInitialized() {
+        val mocks = mutableListOf<Any>()
+        val listener = MockCreationListener { mock, _ -> mocks.add(mock) }
+        Mockito.framework().addListener(listener)
+        EngineTestKit.engine("junit-jupiter")
+            .selectors(
+                selectClass(ExampleTestCase7::class.java)
+            )
+            .execute()
+            .testEvents()
+            .assertThatEvents()
+            .haveExactly(
+                2,
+                event(finishedSuccessfully())
+            )
+
+        assertThat(mocks).allMatch { it is Set<*> }
+        assertThat(mocks.map { it as Set<*> }.toSet()).hasSize(1)
+    }
+
+    @Test
+    fun testCannotRetainAlreadyInitialized() {
+        EngineTestKit.engine("junit-jupiter")
+            .selectors(
+                selectClass(ExampleTestCase8::class.java)
+            )
+            .execute()
+            .testEvents()
+            .assertThatEvents()
+            .haveExactly(
+                1,
+                event(finishedWithFailure(instanceOf(PreconditionViolationException::class.java)))
+            )
+    }
 }