Ruby: add test case for instance variable flow with sqlite3

Author: alexrford

ruby/ql/test/library-tests/frameworks/sqlite3/Sqlite3.expected

@@ -2,7 +2,9 @@ sqlite3SqlConstruction
 | sqlite3.rb:5:1:5:17 | call to execute | sqlite3.rb:5:12:5:17 | <<-SQL |
 | sqlite3.rb:12:8:12:41 | call to prepare | sqlite3.rb:12:19:12:41 | "select * from numbers" |
 | sqlite3.rb:17:3:19:5 | call to execute | sqlite3.rb:17:15:17:35 | "select * from table" |
+| sqlite3.rb:29:7:29:40 | call to execute | sqlite3.rb:29:19:29:39 | "select * from table" |
 sqlite3SqlExecution
 | sqlite3.rb:5:1:5:17 | call to execute | sqlite3.rb:5:12:5:17 | <<-SQL |
 | sqlite3.rb:14:1:14:12 | call to execute | sqlite3.rb:12:8:12:9 | db |
 | sqlite3.rb:17:3:19:5 | call to execute | sqlite3.rb:17:15:17:35 | "select * from table" |
+| sqlite3.rb:29:7:29:40 | call to execute | sqlite3.rb:29:19:29:39 | "select * from table" |

ruby/ql/test/library-tests/frameworks/sqlite3/sqlite3.rb

@@ -18,3 +18,14 @@
     p row
   end
 end
+
+
+class MyDatabaseWrapper
+      def initialize(filename)
+      @db = SQLite3::Database.new(filename, results_as_hash: true)
+    end
+
+    def select_rows(category)
+      @db.execute("select * from table")
+    end
+end