QL: Add tests for FieldOnlyUsedInCharPred.ql

Author: hvitved

ql/ql/test/queries/style/FieldOnlyUsedInCharPred/FieldOnlyUsedInCharPred.expected

@@ -0,0 +1,2 @@
+| FieldOnlyUsedInCharPred.qll:2:3:2:12 | FieldDecl | Field is only used in CharPred. |
+| FieldOnlyUsedInCharPred.qll:22:3:22:11 | FieldDecl | Field is only used in CharPred. |

ql/ql/test/queries/style/FieldOnlyUsedInCharPred/FieldOnlyUsedInCharPred.qll

@@ -0,0 +1,29 @@
+class C1 extends int {
+  int field; // BAD
+
+  C1() {
+    this = field and
+    this = 0
+  }
+}
+
+class C2 extends C1 {
+  int field2; // GOOD
+
+  C2() {
+    this = field2 and
+    this = 0
+  }
+
+  int getField() { result = field2 }
+}
+
+class C3 extends int {
+  C1 field; // GOOD (overridden)
+
+  C3() { this = field }
+}
+
+class C4 extends C3 {
+  override C2 field; // GOOD (overriding)
+}

ql/ql/test/queries/style/FieldOnlyUsedInCharPred/FieldOnlyUsedInCharPred.qlref

@@ -0,0 +1 @@
+queries/style/FieldOnlyUsedInCharPred.ql