Cleanup regex usage in spanner DB driver

- Only compile a regex once for re-use
    - Don't use regex unnecessarily (removing trailing semicolon)
    - Add test for parsing multiple statements in a migration

database/spanner/spanner.go

@@ -209,6 +209,8 @@ func (s *Spanner) Version() (version int, dirty bool, err error) {
 	return version, dirty, nil
 }
 
+var nameMatcher = regexp.MustCompile(`(CREATE TABLE\s(\S+)\s)|(CREATE.+INDEX\s(\S+)\s)`)
+
 // Drop implements database.Driver. Retrieves the database schema first and
 // creates statements to drop the indexes and tables accordingly.
 // Note: The drop statements are created in reverse order to how they're
@@ -227,11 +229,10 @@ func (s *Spanner) Drop() error {
 		return nil
 	}
 
-	r := regexp.MustCompile(`(CREATE TABLE\s(\S+)\s)|(CREATE.+INDEX\s(\S+)\s)`)
 	stmts := make([]string, 0)
 	for i := len(res.Statements) - 1; i >= 0; i-- {
 		s := res.Statements[i]
-		m := r.FindSubmatch([]byte(s))
+		m := nameMatcher.FindSubmatch([]byte(s))
 
 		if len(m) == 0 {
 			continue
@@ -302,11 +303,15 @@ func (s *Spanner) ensureVersionTable() (err error) {
 }
 
 func migrationStatements(migration []byte) []string {
-	regex := regexp.MustCompile(";$")
 	migrationString := string(migration[:])
 	migrationString = strings.TrimSpace(migrationString)
-	migrationString = regex.ReplaceAllString(migrationString, "")
 
-	statements := strings.Split(migrationString, ";")
-	return statements
+	allStatements := strings.Split(migrationString, ";")
+	nonEmptyStatements := allStatements[:0]
+	for _, s := range allStatements {
+		if s != "" {
+			nonEmptyStatements = append(nonEmptyStatements, s)
+		}
+	}
+	return nonEmptyStatements
 }

database/spanner/spanner_test.go

@@ -2,14 +2,20 @@ package spanner
 
 import (
 	"fmt"
-	"github.com/golang-migrate/migrate/v4"
 	"os"
 	"testing"
+)
 
+import (
+	"github.com/golang-migrate/migrate/v4"
 	dt "github.com/golang-migrate/migrate/v4/database/testing"
 	_ "github.com/golang-migrate/migrate/v4/source/file"
 )
 
+import (
+	"github.com/stretchr/testify/assert"
+)
+
 func Test(t *testing.T) {
 	if testing.Short() {
 		t.Skip("skipping test in short mode.")
@@ -51,3 +57,72 @@ func TestMigrate(t *testing.T) {
 	}
 	dt.TestMigrate(t, m, []byte("SELECT 1"))
 }
+
+func TestMultistatementSplit(t *testing.T) {
+	testCases := []struct {
+		name           string
+		multiStatement string
+		expected       []string
+	}{
+		{
+			name:           "single statement, single line, no semicolon",
+			multiStatement: "CREATE TABLE table_name (id STRING(255) NOT NULL) PRIMARY KEY (id)",
+			expected:       []string{"CREATE TABLE table_name (id STRING(255) NOT NULL) PRIMARY KEY (id)"},
+		},
+		{
+			name: "single statement, multi line, no semicolon",
+			multiStatement: `CREATE TABLE table_name (
+	id STRING(255) NOT NULL,
+) PRIMARY KEY (id)`,
+			expected: []string{`CREATE TABLE table_name (
+	id STRING(255) NOT NULL,
+) PRIMARY KEY (id)`},
+		},
+		{
+			name:           "single statement, single line, with semicolon",
+			multiStatement: "CREATE TABLE table_name (id STRING(255) NOT NULL) PRIMARY KEY (id);",
+			expected:       []string{"CREATE TABLE table_name (id STRING(255) NOT NULL) PRIMARY KEY (id)"},
+		},
+		{
+			name: "single statement, multi line, with semicolon",
+			multiStatement: `CREATE TABLE table_name (
+	id STRING(255) NOT NULL,
+) PRIMARY KEY (id);`,
+			expected: []string{`CREATE TABLE table_name (
+	id STRING(255) NOT NULL,
+) PRIMARY KEY (id)`},
+		},
+		{
+			name: "multi statement, with trailing semicolon",
+			// From https://github.com/mattes/migrate/pull/281
+			multiStatement: `CREATE TABLE table_name (
+	id STRING(255) NOT NULL,
+) PRIMARY KEY(id);
+
+CREATE INDEX table_name_id_idx ON table_name (id);`,
+			expected: []string{`CREATE TABLE table_name (
+	id STRING(255) NOT NULL,
+) PRIMARY KEY(id)`, "\n\nCREATE INDEX table_name_id_idx ON table_name (id)"},
+		},
+		{
+			name: "multi statement, no trailing semicolon",
+			// From https://github.com/mattes/migrate/pull/281
+			multiStatement: `CREATE TABLE table_name (
+	id STRING(255) NOT NULL,
+) PRIMARY KEY(id);
+
+CREATE INDEX table_name_id_idx ON table_name (id)`,
+			expected: []string{`CREATE TABLE table_name (
+	id STRING(255) NOT NULL,
+) PRIMARY KEY(id)`, "\n\nCREATE INDEX table_name_id_idx ON table_name (id)"},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			if stmts := migrationStatements([]byte(tc.multiStatement)); !assert.Equal(t, stmts, tc.expected) {
+				t.Error()
+			}
+		})
+	}
+}

go.mod

@@ -33,7 +33,7 @@ require (
 	github.com/satori/go.uuid v1.2.0 // indirect
 	github.com/shopspring/decimal v0.0.0-20180709203117-cd690d0c9e24 // indirect
 	github.com/sirupsen/logrus v1.4.1 // indirect
-	github.com/stretchr/testify v1.3.0 // indirect
+	github.com/stretchr/testify v1.3.0
 	github.com/tidwall/pretty v0.0.0-20180105212114-65a9db5fad51 // indirect
 	github.com/xanzy/go-gitlab v0.15.0
 	github.com/xdg/scram v0.0.0-20180814205039-7eeb5667e42c // indirect