Add test for not generating file facade light class for empty file

compiler/testData/asJava/lightClasses/facades/EmptyFile.java

@@ -0,0 +1 @@
+<not generated>

compiler/testData/asJava/lightClasses/facades/EmptyFile.kt

@@ -0,0 +1,2 @@
+//a.b.c.EmptyFileKt
+package a.b.c

compiler/tests/org/jetbrains/kotlin/asJava/CompilerLightClassTestGenerated.java

@@ -70,6 +70,12 @@ public class CompilerLightClassTestGenerated extends AbstractCompilerLightClassT
             JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/asJava/lightClasses/facades"), Pattern.compile("^(.+)\\.kt$"), true);
         }
 
+        @TestMetadata("EmptyFile.kt")
+        public void testEmptyFile() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/asJava/lightClasses/facades/EmptyFile.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("SingleFile.kt")
         public void testSingleFile() throws Exception {
             String fileName = JetTestUtils.navigationMetadata("compiler/testData/asJava/lightClasses/facades/SingleFile.kt");

compiler/tests/org/jetbrains/kotlin/asJava/LightClassTestCommon.kt

@@ -40,6 +40,14 @@ object LightClassTestCommon {
 
         val lightClass = findLightClass(fqName)
 
+        val actual = actualText(fqName, lightClass, normalizeText)
+        JetTestUtils.assertEqualsToFile(JetTestUtils.replaceExtension(testDataFile, "java"), actual)
+    }
+
+    private fun actualText(fqName: String?, lightClass: PsiClass?, normalizeText: (String) -> String): String {
+        if (lightClass == null) {
+            return "<not generated>"
+        }
         TestCase.assertTrue("Not a light class: $lightClass ($fqName)", lightClass is KotlinLightClass)
 
         val delegate = (lightClass as KotlinLightClass).getDelegate()
@@ -48,6 +56,6 @@ object LightClassTestCommon {
         val buffer = StringBuilder()
         (delegate as ClsElementImpl).appendMirrorText(0, buffer)
         val actual = normalizeText(buffer.toString())
-        JetTestUtils.assertEqualsToFile(JetTestUtils.replaceExtension(testDataFile, "java"), actual)
+        return actual
     }
 }

idea/tests/org/jetbrains/kotlin/idea/caches/resolve/IdeLightClassTestGenerated.java

@@ -43,6 +43,12 @@ public class IdeLightClassTestGenerated extends AbstractIdeLightClassTest {
             JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/asJava/lightClasses/facades"), Pattern.compile("^(.+)\\.kt$"), true);
         }
 
+        @TestMetadata("EmptyFile.kt")
+        public void testEmptyFile() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/asJava/lightClasses/facades/EmptyFile.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("SingleFile.kt")
         public void testSingleFile() throws Exception {
             String fileName = JetTestUtils.navigationMetadata("compiler/testData/asJava/lightClasses/facades/SingleFile.kt");