Do not mark kotlin.test.Test annotated declarations as unused

So #KT-20523 Fixed

idea/src/org/jetbrains/kotlin/idea/inspections/UnusedSymbolInspection.kt

@@ -76,7 +76,14 @@ class UnusedSymbolInspection : AbstractKotlinInspection() {
     companion object {
         private val javaInspection = UnusedDeclarationInspection()
 
+        private val KOTLIN_ADDITIONAL_ANNOTATIONS = listOf("kotlin.test.*")
+
+        private fun KtDeclaration.hasKotlinAdditionalAnnotation() =
+            this is KtNamedDeclaration && checkAnnotatedUsingPatterns(this, KOTLIN_ADDITIONAL_ANNOTATIONS)
+
         fun isEntryPoint(declaration: KtNamedDeclaration): Boolean {
+            if (declaration.hasKotlinAdditionalAnnotation()) return true
+            if (declaration is KtClass && declaration.declarations.any { it.hasKotlinAdditionalAnnotation() }) return true
             val lightElement: PsiElement? = when (declaration) {
                 is KtClassOrObject -> declaration.toLightClass()
                 is KtNamedFunction, is KtSecondaryConstructor -> LightClassUtil.getLightClassMethod(declaration as KtFunction)
@@ -111,6 +118,7 @@ class UnusedSymbolInspection : AbstractKotlinInspection() {
             declaration: KtNamedDeclaration,
             annotationPatterns: Collection<String>
         ): Boolean {
+            if (declaration.annotationEntries.isEmpty()) return false
             val context = declaration.analyze()
             val annotationsPresent = declaration.annotationEntries.mapNotNull {
                 context[BindingContext.ANNOTATION, it]?.fqName?.asString()

idea/testData/multiFileLocalInspections/unusedSymbol/fromKotlinTest/after/kotlin/test/KotlinTest.kt

@@ -0,0 +1,6 @@
+package kotlin.test
+
+annotation class Test
+
+fun assertEquals(expected: Any, actual: Any) {}
+

idea/testData/multiFileLocalInspections/unusedSymbol/fromKotlinTest/after/test.kt

@@ -0,0 +1,10 @@
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class SomeTest {
+
+    @Test
+    fun testSomething() {
+        assertEquals(4, 2 + 2)
+    }
+}

idea/testData/multiFileLocalInspections/unusedSymbol/fromKotlinTest/before/kotlin/test/KotlinTest.kt

@@ -0,0 +1,6 @@
+package kotlin.test
+
+annotation class Test
+
+fun assertEquals(expected: Any, actual: Any) {}
+

idea/testData/multiFileLocalInspections/unusedSymbol/fromKotlinTest/before/test.kt

@@ -0,0 +1,10 @@
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class SomeTest {
+
+    @Test
+    fun <caret>testSomething() {
+        assertEquals(4, 2 + 2)
+    }
+}

idea/testData/multiFileLocalInspections/unusedSymbol/fromKotlinTest/fromKotlinTest.test

@@ -0,0 +1,5 @@
+{
+    "inspectionClass": "org.jetbrains.kotlin.idea.inspections.UnusedSymbolInspection",
+    "problem": "none",
+    "mainFile": "test.kt"
+}

idea/testData/multiFileLocalInspections/unusedSymbol/fromKotlinTestClass/after/kotlin/test/KotlinTest.kt

@@ -0,0 +1,6 @@
+package kotlin.test
+
+annotation class Test
+
+fun assertEquals(expected: Any, actual: Any) {}
+

idea/testData/multiFileLocalInspections/unusedSymbol/fromKotlinTestClass/after/test.kt

@@ -0,0 +1,10 @@
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class SomeTest {
+
+    @Test
+    fun testSomething() {
+        assertEquals(4, 2 + 2)
+    }
+}

idea/testData/multiFileLocalInspections/unusedSymbol/fromKotlinTestClass/before/kotlin/test/KotlinTest.kt

@@ -0,0 +1,6 @@
+package kotlin.test
+
+annotation class Test
+
+fun assertEquals(expected: Any, actual: Any) {}
+

idea/testData/multiFileLocalInspections/unusedSymbol/fromKotlinTestClass/before/test.kt

@@ -0,0 +1,10 @@
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class <caret>SomeTest {
+
+    @Test
+    fun testSomething() {
+        assertEquals(4, 2 + 2)
+    }
+}

idea/testData/multiFileLocalInspections/unusedSymbol/fromKotlinTestClass/fromKotlinTestClass.test

@@ -0,0 +1,5 @@
+{
+    "inspectionClass": "org.jetbrains.kotlin.idea.inspections.UnusedSymbolInspection",
+    "problem": "none",
+    "mainFile": "test.kt"
+}

idea/tests/org/jetbrains/kotlin/idea/inspections/MultiFileLocalInspectionTestGenerated.java

@@ -78,4 +78,14 @@ public class MultiFileLocalInspectionTestGenerated extends AbstractMultiFileLoca
     public void testReconcilePackageWithDirectory_packageMatchesDirectory_PackageMatchesDirectory() throws Exception {
         runTest("idea/testData/multiFileLocalInspections/reconcilePackageWithDirectory/packageMatchesDirectory/packageMatchesDirectory.test");
     }
+
+    @TestMetadata("unusedSymbol/fromKotlinTest/fromKotlinTest.test")
+    public void testUnusedSymbol_fromKotlinTest_FromKotlinTest() throws Exception {
+        runTest("idea/testData/multiFileLocalInspections/unusedSymbol/fromKotlinTest/fromKotlinTest.test");
+    }
+
+    @TestMetadata("unusedSymbol/fromKotlinTestClass/fromKotlinTestClass.test")
+    public void testUnusedSymbol_fromKotlinTestClass_FromKotlinTestClass() throws Exception {
+        runTest("idea/testData/multiFileLocalInspections/unusedSymbol/fromKotlinTestClass/fromKotlinTestClass.test");
+    }
 }