Use spanner cloud emulator to run tests

Addresses: golang-migrate#410

database/spanner/spanner_test.go

@@ -8,52 +8,57 @@ import (
 	"github.com/golang-migrate/migrate/v4"
 
 	dt "github.com/golang-migrate/migrate/v4/database/testing"
-
 	_ "github.com/golang-migrate/migrate/v4/source/file"
+
+	"cloud.google.com/go/spanner/spannertest"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
-func Test(t *testing.T) {
-	if testing.Short() {
-		t.Skip("skipping test in short mode.")
+// withSpannerEmulator is not thread-safe and cannot be used with parallel tests since it sets the emulator
+func withSpannerEmulator(t *testing.T, testFunc func(t *testing.T)) {
+	t.Helper()
+	srv, err := spannertest.NewServer("localhost:0")
+	if err != nil {
+		t.Fatal("Failed to create Spanner emulator:", err)
 	}
-
-	db, ok := os.LookupEnv("SPANNER_DATABASE")
-	if !ok {
-		t.Skip("SPANNER_DATABASE not set, skipping test.")
+	// This is not thread-safe
+	if err := os.Setenv("SPANNER_EMULATOR_HOST", srv.Addr); err != nil {
+		t.Fatal("Failed to set SPANNER_EMULATOR_HOST env var:", err)
 	}
+	defer srv.Close()
+	testFunc(t)
 
-	s := &Spanner{}
-	addr := fmt.Sprintf("spanner://%s", db)
-	d, err := s.Open(addr)
-	if err != nil {
-		t.Fatal(err)
-	}
-	dt.Test(t, d, []byte("SELECT 1"))
 }
 
-func TestMigrate(t *testing.T) {
-	if testing.Short() {
-		t.Skip("skipping test in short mode.")
-	}
+const db = "projects/abc/instances/def/databases/testdb"
 
-	db, ok := os.LookupEnv("SPANNER_DATABASE")
-	if !ok {
-		t.Skip("SPANNER_DATABASE not set, skipping test.")
-	}
+func Test(t *testing.T) {
+	withSpannerEmulator(t, func(t *testing.T) {
+		uri := fmt.Sprintf("spanner://%s", db)
+		s := &Spanner{}
+		d, err := s.Open(uri)
+		if err != nil {
+			t.Fatal(err)
+		}
+		dt.Test(t, d, []byte("CREATE TABLE test (id BOOL) PRIMARY KEY (id)"))
+	})
+}
 
-	s := &Spanner{}
-	addr := fmt.Sprintf("spanner://%s", db)
-	d, err := s.Open(addr)
-	if err != nil {
-		t.Fatal(err)
-	}
-	m, err := migrate.NewWithDatabaseInstance("file://./examples/migrations", db, d)
-	if err != nil {
-		t.Fatal(err)
-	}
-	dt.TestMigrate(t, m)
+func TestMigrate(t *testing.T) {
+	withSpannerEmulator(t, func(t *testing.T) {
+		s := &Spanner{}
+		uri := fmt.Sprintf("spanner://%s", db)
+		d, err := s.Open(uri)
+		if err != nil {
+			t.Fatal(err)
+		}
+		m, err := migrate.NewWithDatabaseInstance("file://./examples/migrations", uri, d)
+		if err != nil {
+			t.Fatal(err)
+		}
+		dt.TestMigrate(t, m)
+	})
 }
 
 func TestCleanStatements(t *testing.T) {