chore: Add tests for no-constant-binary-expression

Author: retyui

Diff for: test/no-constant-binary-expression.js

@@ -0,0 +1,7 @@
+/*eslint-disable no-undef,no-unused-vars*/
+
+// Incorrect
+const value1 = !foo == null; // eslint-disable-line no-constant-binary-expression
+
+// Correct
+const value2 = !(foo == null);