fix: additional checks for 'if' blocks inside loops (#809)

jadx-core/src/test/java/jadx/tests/integration/loops/TestDoWhileBreak2.java

@@ -0,0 +1,47 @@
+package jadx.tests.integration.loops;
+
+import java.util.Arrays;
+import java.util.Iterator;
+
+import org.junit.jupiter.api.Test;
+
+import jadx.tests.api.IntegrationTest;
+
+import static jadx.tests.api.utils.assertj.JadxAssertions.assertThat;
+
+public class TestDoWhileBreak2 extends IntegrationTest {
+
+	public static class TestCls {
+		Iterator<String> it;
+
+		@SuppressWarnings("ConstantConditions")
+		public Object test() {
+			String obj;
+			do {
+				obj = this.it.next();
+				if (obj == null) {
+					return obj; // 'return null' works
+				}
+			} while (this.it.hasNext());
+			return obj;
+		}
+
+		public void check() {
+			this.it = Arrays.asList("a", "b").iterator();
+			assertThat(test()).isEqualTo("b");
+
+			this.it = Arrays.asList("a", "b", null).iterator();
+			assertThat(test()).isEqualTo(null);
+		}
+	}
+
+	@Test
+	public void test() {
+		assertThat(getClassNode(TestCls.class))
+				.code()
+				.containsLine(2, "do {")
+				.containsLine(3, "obj = this.it.next();")
+				.containsLine(3, "if (obj == null) {")
+				.containsLine(2, "} while (this.it.hasNext());");
+	}
+}

jadx-core/src/test/java/jadx/tests/integration/loops/TestDoWhileBreak3.java

@@ -0,0 +1,33 @@
+package jadx.tests.integration.loops;
+
+import java.util.Iterator;
+
+import org.junit.jupiter.api.Test;
+
+import jadx.NotYetImplemented;
+import jadx.tests.api.IntegrationTest;
+
+import static jadx.tests.api.utils.assertj.JadxAssertions.assertThat;
+
+public class TestDoWhileBreak3 extends IntegrationTest {
+
+	public static class TestCls {
+		Iterator<String> it;
+
+		public void test() {
+			do {
+				if (!it.hasNext()) {
+					break;
+				}
+			} while (it.next() != null);
+		}
+	}
+
+	@NotYetImplemented
+	@Test
+	public void test() {
+		assertThat(getClassNode(TestCls.class))
+				.code()
+				.containsOnlyOnce("while");
+	}
+}