expose database in connection

get/return from pool while result set is been used. still single connection pool

spec/std/db/db_spec.cr

@@ -13,20 +13,18 @@ describe DB do
 
   it "should instantiate driver with connection uri" do
     db = DB.open "dummy://localhost:1027"
-    db.driver_class.should eq(DummyDriver)
+    db.driver.should be_a(DummyDriver)
     db.uri.scheme.should eq("dummy")
     db.uri.host.should eq("localhost")
     db.uri.port.should eq(1027)
   end
 
   it "should create a connection and close it" do
-    cnn = nil
+    DummyDriver::DummyConnection.clear_connections
     DB.open "dummy://localhost" do |db|
-      cnn = db.connection
     end
-
-    cnn.should be_a(DummyDriver::DummyConnection)
-    cnn.not_nil!.closed?.should be_true
+    connections.size.should eq(1)
+    connections.first.closed?.should be_true
   end
 
   it "query should close result_set" do
@@ -61,4 +59,14 @@ describe DB do
     end
     connections.first.closed?.should be_true
   end
+
+  it "should raise if the sole connection is been used" do
+    with_dummy do |db|
+      db.query "1" do |rs|
+        expect_raises Exception, /DB Pool Exhausted/ do
+          db.scalar "2"
+        end
+      end
+    end
+  end
 end

spec/std/db/dummy_driver.cr

@@ -1,14 +1,13 @@
 require "spec"
 
 class DummyDriver < DB::Driver
-  def build_connection
-    DummyConnection.new(uri)
+  def build_connection(db : DB::Database) : DB::Connection
+    DummyConnection.new(db)
   end
 
   class DummyConnection < DB::Connection
-    getter uri
-
-    def initialize(@uri)
+    def initialize(db)
+      super(db)
       @@connections ||= [] of DummyConnection
       @@connections.not_nil! << self
     end
@@ -60,6 +59,7 @@ class DummyDriver < DB::Driver
     end
 
     protected def do_close
+      super
     end
   end
 
@@ -74,6 +74,7 @@ class DummyDriver < DB::Driver
     end
 
     protected def do_close
+      super
     end
 
     def self.last_result_set