concurrency support, closes #20 and closes #9 and closes #15

* c600769 do not require a connection name, unique dsn is generated
* 1b20b9c update travis
* 1097b6a add comments for godoc documentation
* c142a95 fix golint reported issues

driver.go

@@ -0,0 +1,56 @@
+package sqlmock
+
+import (
+	"database/sql"
+	"database/sql/driver"
+	"fmt"
+	"sync"
+)
+
+var pool *mockDriver
+
+func init() {
+	pool = &mockDriver{
+		conns: make(map[string]*Sqlmock),
+	}
+	sql.Register("sqlmock", pool)
+}
+
+type mockDriver struct {
+	sync.Mutex
+	counter int
+	conns   map[string]*Sqlmock
+}
+
+func (d *mockDriver) Open(dsn string) (driver.Conn, error) {
+	d.Lock()
+	defer d.Unlock()
+
+	c, ok := d.conns[dsn]
+	if !ok {
+		return c, fmt.Errorf("expected a connection to be available, but it is not")
+	}
+
+	c.opened++
+	return c, nil
+}
+
+// New creates sqlmock database connection
+// and a mock to manage expectations.
+// Pings db so that all expectations could be
+// asserted.
+func New() (db *sql.DB, mock *Sqlmock, err error) {
+	pool.Lock()
+	dsn := fmt.Sprintf("sqlmock_db_%d", pool.counter)
+	pool.counter++
+
+	mock = &Sqlmock{dsn: dsn, drv: pool}
+	pool.conns[dsn] = mock
+	pool.Unlock()
+
+	db, err = sql.Open("sqlmock", dsn)
+	if err != nil {
+		return
+	}
+	return db, mock, db.Ping()
+}