GROOVY-11769: add test case

Author: eric-milles

src/test/groovy/groovy/transform/stc/CoercionSTCTest.groovy

@@ -211,6 +211,21 @@ class CoercionSTCTest extends StaticTypeCheckingTestCase {
  '''
  }
 
+ void testCastObjectToInterface() {
+ assertScript '''
+ List<Object> m(object) {
+ if (object == null) return new ArrayList<>()
+ if (object instanceof Collection) return new ArrayList<Object>((Collection) object)
+ return [object]
+ }
+ def item = 0
+ def list = [1,2]
+ assert m(null).size() == 0
+ assert m(item).size() == 1
+ assert m(list).size() == 2
+ '''
+ }
+
  void testCastInterfaceToSubclass() {
  assertScript '''
  interface A {

src/test/groovy/org/codehaus/groovy/classgen/asm/sc/CoercionStaticCompileTests.groovy

@@ -24,4 +24,12 @@ import groovy.transform.stc.CoercionSTCTest
  * Unit tests for static compilation : coercions.
  */
 final class CoercionStaticCompileTests extends CoercionSTCTest implements StaticCompilationTestSupport {
+
+ @Override // GROOVY-11769
+ void testCastObjectToInterface() {
+ super.testCastObjectToInterface()
+ String bytecode = astTrees.values()[0][1]
+ bytecode = bytecode.substring(bytecode.indexOf('m(Ljava/lang/Object;)'))
+ assert bytecode.count('CHECKCAST') == 1 // guarded typecast isn't groovy
+ }
 }