add ResultSet#exec to ensure the query is performed. By default generates a move_next.

spec/std/db/db_spec.cr

@@ -50,4 +50,12 @@ describe DB do
       db.connection.last_statement.closed?.should be_true
     end
   end
+
+  it "exec should perform statement" do
+    with_dummy do |db|
+      db.exec ""
+      DummyDriver::DummyResultSet.last_result_set.executed?.should be_true
+      db.connection.last_statement.closed?.should be_true
+    end
+  end
 end

spec/std/db/dummy_driver.cr

@@ -43,9 +43,20 @@ class DummyDriver < DB::Driver
   class DummyResultSet < DB::ResultSet
     def initialize(statement, @iterator)
       super(statement)
+      @executed = false
+      @@last_result_set = self
+    end
+
+    def self.last_result_set
+      @@last_result_set.not_nil!
+    end
+
+    def executed?
+      @executed
     end
 
     def move_next
+      @executed = true
       @iterator.next.tap do |n|
         return false if n.is_a?(Iterator::Stop)
         @values = n.each