Add versioning to perf SQL database

perf/go/db/db_test.go

Index: perf/go/db/db_test.go
diff --git a/perf/go/db/db_test.go b/perf/go/db/db_test.go
new file mode 100644
index 0000000000000000000000000000000000000000..5cb84ff824a158912515405501a625c1fc09426d
--- /dev/null
+++ b/perf/go/db/db_test.go
@@ -0,0 +1,49 @@
+package db
+
+import (
+	"fmt"
+	"os"
+	"testing"
+)
+
+import (
+	// Using 'require' which is like using 'assert' but causes tests to fail.
+	assert "github.com/stretchr/testify/require"
+)
+
+// Connection string to the local MySQL database for testing.

[jcgregorio, 2014/09/30 14:54:08]

So I need a local MySQL instance to run this test?

[stephana, 2014/09/30 18:11:50]

Yes. I have changed it so that it checks whether the env variable is set and
skips the test with a log message if not set. 
(and still test against SQLite).

+const MYSQL_DB_OPEN = "root:%s@tcp(localhost:3306)/skia?parseTime=true"
+
+func TestDBVersioning(t *testing.T) {
+	// Initialize without argument to test against SQLite3
+	Init("")
+	assert.False(t, isMySQL)
+	testDBVersioning(t)
+
+	// Initialize to test against local MySQL db
+	Init(fmt.Sprintf(MYSQL_DB_OPEN, os.Getenv("MYSQL_TESTING_ROOTPW")))
+	assert.True(t, isMySQL)
+	testDBVersioning(t)
+}
+
+// Test wether the migration scripts execute.
+func testDBVersioning(t *testing.T) {
+	// get the DB version
+	dbVersion, err := DBVersion()
+	assert.Nil(t, err)
+	maxVersion := MaxDBVersion()
+
+	// downgrade to 0
+	err = Migrate(0)
+	assert.Nil(t, err)
+	dbVersion, err = DBVersion()
+	assert.Nil(t, err)
+	assert.Equal(t, 0, dbVersion)
+
+	// upgrade the the latest version
+	err = Migrate(maxVersion)
+	assert.Nil(t, err)
+	dbVersion, err = DBVersion()
+	assert.Nil(t, err)
+	assert.Equal(t, maxVersion, dbVersion)
+}