core: test enum implementing interface

jadx-core/src/test/java/jadx/tests/integration/enums/TestEnumsInterface.java

+package jadx.tests.integration.enums;
+
+import jadx.core.dex.nodes.ClassNode;
+import jadx.tests.api.IntegrationTest;
+import jadx.tests.api.utils.JadxMatchers;
+import org.junit.Test;
+
+import static org.junit.Assert.assertThat;
+
+public class TestEnumsInterface extends IntegrationTest {
+
+	public static class TestCls {
+
+		public enum Operation implements IOperation {
+			PLUS {
+				public int apply(int x, int y) {
+					return x + y;
+				}
+			},
+			MINUS {
+				public int apply(int x, int y) {
+					return x - y;
+				}
+			};
+		}
+
+		public interface IOperation {
+			int apply(int x, int y);
+		}
+	}
+
+	@Test
+	public void test() {
+		ClassNode cls = getClassNode(TestCls.class);
+		String code = cls.getCode().toString();
+
+		assertThat(code, JadxMatchers.containsLines(1,
+				"public enum Operation implements IOperation {",
+				indent(1) + "PLUS {",
+				indent(2) + "public int apply(int x, int y) {",
+				indent(3) + "return x + y;",
+				indent(2) + "}",
+				indent(1) + "},",
+				indent(1) + "MINUS {",
+				indent(2) + "public int apply(int x, int y) {",
+				indent(3) + "return x - y;",
+				indent(2) + "}",
+				indent(1) + "}",
+				"}"
+		));
+	}
+}