Add tests

spotbugs-tests/src/test/java/edu/umd/cs/findbugs/detect/Issue2640Test.java

@@ -0,0 +1,12 @@
+package edu.umd.cs.findbugs.detect;
+
+import edu.umd.cs.findbugs.AbstractIntegrationTest;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+class Issue2640Test extends AbstractIntegrationTest {
+    @Test
+    void testIssue() {
+        Assertions.assertDoesNotThrow(() -> performAnalysis("ghIssues/Issue2640.class"));
+    }
+}

spotbugsTestCases/src/java/ghIssues/Issue2640.java

@@ -0,0 +1,8 @@
+package ghIssues;
+
+public class Issue2640 {
+    public void testUnreachableCode() {
+        org.junit.Assert.fail();
+        System.err.println("Not reachable code");
+    }
+}