Add test case for EmptySwitchEliminator

src/test/java/soot/jimple/toolkits/scalar/EmptySwitchEliminatorTest.java

@@ -0,0 +1,105 @@
+package soot.jimple.toolkits.scalar;
+
+/*-
+ * #%L
+ * Soot - a J*va Optimization Framework
+ * %%
+ * Copyright (C) 1997 - 2020 Raja Vallee-Rai and others
+ * %%
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation, either version 2.1 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Lesser Public License for more details.
+ *
+ * You should have received a copy of the GNU General Lesser Public
+ * License along with this program.  If not, see
+ * <http://www.gnu.org/licenses/lgpl-2.1.html>.
+ * #L%
+ */
+
+import org.junit.Test;
+import soot.*;
+import soot.jimple.IntConstant;
+import soot.jimple.Jimple;
+import soot.jimple.JimpleBody;
+import soot.jimple.LookupSwitchStmt;
+import soot.jimple.internal.JGotoStmt;
+import soot.util.Chain;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Iterator;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+public class EmptySwitchEliminatorTest {
+
+    /**
+     * The test is ported from https://github.com/soot-oss/SootUp/blob/develop/sootup.java.bytecode/src/test/java/sootup/java/bytecode/interceptors/EmptySwitchEliminatorTest.java
+     */
+    @Test
+    public void testEmptySwitch() {
+        // build test method and body
+        SootClass cl = new SootClass("TestClass", Modifier.PUBLIC);
+        SootMethod method = new SootMethod("test", Collections.emptyList(), VoidType.v(), Modifier.PUBLIC);
+        cl.addMethod(method);
+        JimpleBody body = Jimple.v().newBody(method);
+        method.setActiveBody(body);
+
+        // build locals
+        Local l0 = Jimple.v().newLocal("l0", IntType.v());
+        Local l1 = Jimple.v().newLocal("l1", IntType.v());
+        Local l2 = Jimple.v().newLocal("l2", IntType.v());
+        Chain<Local> locals = body.getLocals();
+        locals.add(l0);
+        locals.add(l1);
+        locals.add(l2);
+
+        // build statements
+        Unit startingStmt = Jimple.v().newIdentityStmt(l0, Jimple.v().newThisRef(method.getDeclaringClass().getType()));
+        Unit stmt1 = Jimple.v().newAssignStmt(l1, IntConstant.v(3));
+        Unit defaultStmt = Jimple.v().newAssignStmt(l2, IntConstant.v(0));
+        LookupSwitchStmt sw = Jimple.v().newLookupSwitchStmt(l1, new ArrayList<>(), new ArrayList<>(), defaultStmt);
+        Unit ret = Jimple.v().newReturnVoidStmt();
+
+        /*
+            l0 := @this: TestClass
+            l1 = 3
+            lookupswitch(l1) {
+                default:
+                    goto l2 = 0;
+            }
+            return
+         */
+        UnitPatchingChain units = body.getUnits();
+        units.add(startingStmt);
+        units.add(stmt1);
+        units.add(sw);
+        units.add(ret);
+
+        // execute transform
+        EmptySwitchEliminator.v().internalTransform(body, "testPhase", Collections.emptyMap());
+
+        // check resulting code (switch should be removed)
+        /*
+            Expected:
+                l0 := @this: TestClass
+                l1 = 3
+                goto [?= l2 = 0]
+                return
+        */
+        Iterator<Unit> it = units.iterator();
+        assertEquals(startingStmt, it.next());
+        assertEquals(stmt1, it.next());
+        Unit stmt3 = it.next();
+        assertTrue(stmt3 instanceof JGotoStmt);
+        assertEquals(defaultStmt, ((JGotoStmt) stmt3).getTargetBox().getUnit());
+        assertEquals(ret, it.next());
+    }
+}