Merge pull request #2640 from aschackmull/java/nullness-fp-tests

Java: Document two FPs with unit tests.

Author: yo-h

java/ql/test/query-tests/Nullness/C.java

@@ -168,4 +168,44 @@ public void ex12() {
       finalObj.hashCode(); // OK
     }
   }
+
+  private void verifyBool(boolean b) {
+    if (!b) {
+      throw new Exception();
+    }
+  }
+
+  public void ex13(int[] a) {
+    int i = 0;
+    boolean b = false;
+    Object obj = null;
+    while (a[++i] != 0) {
+      if (a[i] == 1) {
+        obj = new Object();
+        b = true;
+      } else if (a[i] == 2) {
+        verifyBool(b);
+        obj.hashCode(); // NPE - false positive
+      }
+    }
+  }
+
+  private void verifyNotNull(Object obj) {
+    if (obj == null) {
+      throw new Exception();
+    }
+  }
+
+  public void ex14(int[] a) {
+    int i = 0;
+    Object obj = null;
+    while (a[++i] != 0) {
+      if (a[i] == 1) {
+        obj = new Object();
+      } else if (a[i] == 2) {
+        verifyNotNull(obj);
+        obj.hashCode(); // NPE - false positive
+      }
+    }
+  }
 }

java/ql/test/query-tests/Nullness/NullMaybe.expected

@@ -28,5 +28,7 @@
 | C.java:110:25:110:27 | obj | Variable $@ may be null here because of $@ assignment. | C.java:106:5:106:30 | Object obj | obj | C.java:118:13:118:22 | ...=... | this |
 | C.java:137:7:137:10 | obj2 | Variable $@ may be null here as suggested by $@ null guard. | C.java:131:5:131:23 | Object obj2 | obj2 | C.java:132:9:132:20 | ... != ... | this |
 | C.java:144:15:144:15 | a | Variable $@ may be null here as suggested by $@ null guard. | C.java:141:20:141:26 | a | a | C.java:142:13:142:21 | ... == ... | this |
+| C.java:188:9:188:11 | obj | Variable $@ may be null here because of $@ assignment. | C.java:181:5:181:22 | Object obj | obj | C.java:181:12:181:21 | obj | this |
+| C.java:207:9:207:11 | obj | Variable $@ may be null here because of $@ assignment. | C.java:201:5:201:22 | Object obj | obj | C.java:201:12:201:21 | obj | this |
 | F.java:11:5:11:7 | obj | Variable $@ may be null here as suggested by $@ null guard. | F.java:8:18:8:27 | obj | obj | F.java:9:9:9:19 | ... == ... | this |
 | F.java:17:5:17:7 | obj | Variable $@ may be null here as suggested by $@ null guard. | F.java:14:18:14:27 | obj | obj | F.java:15:9:15:19 | ... == ... | this |