database/sql: add OpenDB to directly create a *DB without a DSN.

The current Open method limits the ability for driver maintainers
to expose options for their drivers by forcing all the configuration
to pass through the DSN in order to create a *DB.

This CL allows driver maintainers to write their own initialization
functions that return a *DB making configuration of the underlying
drivers easier.

Fixes #20268

Change-Id: Ib10b794f36a201bbb92c23999c8351815d38eedb
Reviewed-on: https://go-review.googlesource.com/53430
Reviewed-by: Daniel Theophanes <kardianos@gmail.com>
Run-TryBot: Daniel Theophanes <kardianos@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

1 files changed, 13 insertions, 6 deletions

diff --git a/src/database/sql/sql_test.go b/src/database/sql/sql_test.go
index bcf0887d0e..fe7c3278c7 100644
--- a/src/database/sql/sql_test.go
+++ b/src/database/sql/sql_test.go
@@ -81,6 +81,13 @@ func newTestDB(t testing.TB, name string) *DB {
 	return db
 }
 
+func TestOpenDB(t *testing.T) {
+	db := OpenDB(dsnConnector{dsn: fakeDBName, driver: fdriver})
+	if db.Driver() != fdriver {
+		t.Fatalf("OpenDB should return the driver of the Connector")
+	}
+}
+
 func TestDriverPanic(t *testing.T) {
 	// Test that if driver panics, database/sql does not deadlock.
 	db, err := Open("test", fakeDBName)
@@ -1672,7 +1679,7 @@ func TestIssue4902(t *testing.T) {
 	db := newTestDB(t, "people")
 	defer closeDB(t, db)
 
-	driver := db.driver.(*fakeDriver)
+	driver := db.Driver().(*fakeDriver)
 	opens0 := driver.openCount
 
 	var stmt *Stmt
@@ -1765,7 +1772,7 @@ func TestMaxOpenConns(t *testing.T) {
 	db := newTestDB(t, "magicquery")
 	defer closeDB(t, db)
 
-	driver := db.driver.(*fakeDriver)
+	driver := db.Driver().(*fakeDriver)
 
 	// Force the number of open connections to 0 so we can get an accurate
 	// count for the test
@@ -2057,7 +2064,7 @@ func TestConnMaxLifetime(t *testing.T) {
 	db := newTestDB(t, "magicquery")
 	defer closeDB(t, db)
 
-	driver := db.driver.(*fakeDriver)
+	driver := db.Driver().(*fakeDriver)
 
 	// Force the number of open connections to 0 so we can get an accurate
 	// count for the test
@@ -2146,7 +2153,7 @@ func TestStmtCloseDeps(t *testing.T) {
 	db := newTestDB(t, "magicquery")
 	defer closeDB(t, db)
 
-	driver := db.driver.(*fakeDriver)
+	driver := db.Driver().(*fakeDriver)
 
 	driver.mu.Lock()
 	opens0 := driver.openCount
@@ -3071,7 +3078,7 @@ func TestIssue6081(t *testing.T) {
 	db := newTestDB(t, "people")
 	defer closeDB(t, db)
 
-	drv := db.driver.(*fakeDriver)
+	drv := db.Driver().(*fakeDriver)
 	drv.mu.Lock()
 	opens0 := drv.openCount
 	closes0 := drv.closeCount
@@ -3326,7 +3333,7 @@ func TestConnectionLeak(t *testing.T) {
 	// Now we have defaultMaxIdleConns busy connections. Open
 	// a new one, but wait until the busy connections are released
 	// before returning control to DB.
-	drv := db.driver.(*fakeDriver)
+	drv := db.Driver().(*fakeDriver)
 	drv.waitCh = make(chan struct{}, 1)
 	drv.waitingCh = make(chan struct{}, 1)
 	var wg sync.WaitGroup