allow connection initialization

spec/database_spec.cr

@@ -0,0 +1,42 @@
+require "./spec_helper"
+
+describe DB::Database do
+  it "allows connection initialization" do
+    cnn_setup = 0
+    DB.open "dummy://localhost:1027?initial_pool_size=2&max_pool_size=4&max_idle_pool_size=1" do |db|
+      cnn_setup.should eq(0)
+
+      db.setup_connection do |cnn|
+        cnn_setup += 1
+      end
+
+      cnn_setup.should eq(2)
+
+      db.using_connection do
+        cnn_setup.should eq(2)
+        db.using_connection do
+          cnn_setup.should eq(2)
+          db.using_connection do
+            cnn_setup.should eq(3)
+            db.using_connection do
+              cnn_setup.should eq(4)
+            end
+            # the pool didn't shrink no new initialization should be done next
+            db.using_connection do
+              cnn_setup.should eq(4)
+            end
+          end
+          # the pool shrink 1. max_idle_pool_size=1
+          # after the previous end there where 2.
+          db.using_connection do
+            cnn_setup.should eq(4)
+            # so now there will be a new connection created
+            db.using_connection do
+              cnn_setup.should eq(5)
+            end
+          end
+        end
+      end
+    end
+  end
+end