feat: added pitest and improved test suite.

Author: jrfaller

core/build.gradle

@@ -1,3 +1,7 @@
+plugins {
+    id 'info.solidsoft.pitest' version '1.7.0'
+}
+
 description = 'GumTree core module.'
 
 dependencies {
@@ -7,6 +11,15 @@ dependencies {
 	implementation 'org.jgrapht:jgrapht-core:1.5.1'
 }
 
+pitest {
+    targetClasses = ['com.github.gumtreediff.tree*']
+	targetTests = ['com.github.gumtreediff.test.TestTree', 'com.github.gumtreediff.test.TestMetadata', 'com.github.gumtreediff.test.TestTreeUtils']
+    threads = 4
+    outputFormats = ['XML', 'HTML']
+    timestampedReports = false
+    junit5PluginVersion = '0.15'
+}
+
 allprojects {
 	gradle.projectsEvaluated {
 		tasks.withType(JavaCompile) {

core/src/test/java/com/github/gumtreediff/test/TestTree.java

@@ -27,8 +27,6 @@
 import com.github.gumtreediff.tree.*;
 import org.junit.jupiter.api.Test;
 
-import javax.lang.model.type.ArrayType;
-
 import static org.junit.jupiter.api.Assertions.*;
 
 public class TestTree {
@@ -52,6 +50,27 @@ public void testSearchSubtree() {
         assertEquals(0, results.size());
     }
 
+    @Test
+    public void testIsRoot() {
+        Tree tree = new DefaultTree(TypeSet.type("a"));
+        tree.addChild(new DefaultTree(TypeSet.type("b")));
+        tree.addChild(new DefaultTree(TypeSet.type("c"), "foo"));
+        assertTrue(tree.isRoot());
+        assertFalse(tree.getChild(0).isRoot());
+        assertFalse(tree.getChild(1).isRoot());
+    }
+
+    @Test
+    public void testInsertChild() {
+        Tree tree = new DefaultTree(TypeSet.type("a"));
+        tree.addChild(new DefaultTree(TypeSet.type("b")));
+        tree.addChild(new DefaultTree(TypeSet.type("c"), "foo"));
+        System.out.println(tree.getChildren().size());
+        tree.insertChild(new DefaultTree(TypeSet.type("m")), 1);
+        assertEquals(TypeSet.type("m"), tree.getChild(1).getType());
+        assertEquals(tree, tree.getChild(1).getParent());
+    }
+
     @Test
     public void testTreesBetweenPositions() {
         Tree root = TreeLoader.getDummySrc();
@@ -179,7 +198,9 @@ public void testIsostructure() {
         assertTrue(root.isIsoStructuralTo(rootCpy));
         rootCpy.getChild("0.0").setLabel("foo");
         assertTrue(root.isIsoStructuralTo(rootCpy));
-        root.getChild("0.0").setLabel("foo");
+        rootCpy.getChild("0.1").setType(TypeSet.type("foo"));
+        assertFalse(root.isIsoStructuralTo(rootCpy));
+        root.getChild("0.1").setType(TypeSet.type("foo"));
         assertTrue(root.isIsoStructuralTo(rootCpy));
         root.addChild(new FakeTree());
         assertFalse(root.isIsoStructuralTo(rootCpy));
@@ -232,6 +253,13 @@ public void testFakeTree() {
 
     @Test
     public void testTypesAndLabels() {
+        Type origType = TypeSet.type("anewtype");
+        Type otherType = TypeSet.type("othernewtype");
+        Type origCopyType = TypeSet.type("anewtype");
+        assertNotNull(origType);
+        assertSame(origType, origCopyType);
+        assertNotEquals(origType, otherType);
+        assertEquals("anewtype", origType.name);
         Tree t1 = new DefaultTree(TypeSet.type("foo"));
         Tree t2 = new DefaultTree(TypeSet.type("foo"));
         assertTrue(t1.hasSameType(t2));