migration: implement dry mode in Run

Also receive a writer for logging process.

Related to #1137.

migration/migration.go

@@ -9,6 +9,8 @@ package migration
 
 import (
 	"errors"
+	"fmt"
+	"io"
 
 	"github.com/tsuru/tsuru/db"
 	"github.com/tsuru/tsuru/db/storage"
@@ -46,7 +48,7 @@ func Register(name string, fn MigrateFunc) error {
 
 // Run runs all registered migrations. Migrations are executed in the order
 // that they were registered.
-func Run() error {
+func Run(w io.Writer, dry bool) error {
 	migrations, err := getMigrations()
 	if err != nil {
 		return err
@@ -57,15 +59,19 @@ func Run() error {
 	}
 	defer coll.Close()
 	for _, m := range migrations {
-		err := m.fn()
-		if err != nil {
-			return err
-		}
-		m.Ran = true
-		err = coll.Insert(m)
-		if err != nil {
-			return err
+		fmt.Fprintf(w, "Running %q... ", m.Name)
+		if !dry {
+			err := m.fn()
+			if err != nil {
+				return err
+			}
+			m.Ran = true
+			err = coll.Insert(m)
+			if err != nil {
+				return err
+			}
 		}
+		fmt.Fprintln(w, "OK")
 	}
 	return nil
 }

migration/migration_test.go

@@ -5,6 +5,7 @@
 package migration
 
 import (
+	"bytes"
 	"errors"
 	"testing"
 
@@ -44,6 +45,11 @@ func (s *Suite) TearDownSuite(c *check.C) {
 }
 
 func (s *Suite) TestRun(c *check.C) {
+	expected := `Running "migration1"... OK
+Running "migration2"... OK
+Running "migration3"... OK
+`
+	var buf bytes.Buffer
 	var runs []string
 	var mFunc = func(name string) MigrateFunc {
 		return func() error {
@@ -57,12 +63,14 @@ func (s *Suite) TestRun(c *check.C) {
 	c.Assert(err, check.IsNil)
 	err = Register("migration3", mFunc("migration3"))
 	c.Assert(err, check.IsNil)
-	err = Run()
+	err = Run(&buf, false)
 	c.Assert(err, check.IsNil)
 	c.Assert(runs, check.DeepEquals, []string{"migration1", "migration2", "migration3"})
+	c.Assert(buf.String(), check.Equals, expected)
 }
 
 func (s *Suite) TestMultipleRuns(c *check.C) {
+	var buf bytes.Buffer
 	var runs []string
 	var mFunc = func(name string) MigrateFunc {
 		return func() error {
@@ -76,7 +84,7 @@ func (s *Suite) TestMultipleRuns(c *check.C) {
 	c.Assert(err, check.IsNil)
 	err = Register("migration3", mFunc("migration3"))
 	c.Assert(err, check.IsNil)
-	err = Run()
+	err = Run(&buf, false)
 	c.Assert(err, check.IsNil)
 	migrations = nil
 	err = Register("migration1", mFunc("migration1"))
@@ -87,14 +95,15 @@ func (s *Suite) TestMultipleRuns(c *check.C) {
 	c.Assert(err, check.IsNil)
 	err = Register("migration3", mFunc("migration3"))
 	c.Assert(err, check.IsNil)
-	err = Run()
+	err = Run(&buf, false)
 	c.Assert(err, check.IsNil)
 	c.Assert(runs, check.DeepEquals, []string{"migration1", "migration2", "migration3", "migration4"})
 }
 
 func (s *Suite) TestFailingMigration(c *check.C) {
 	var runs []string
 	var calls int
+	var buf bytes.Buffer
 	err := Register("mig1", func() error {
 		if calls == 1 {
 			runs = append(runs, "mig1")
@@ -109,15 +118,40 @@ func (s *Suite) TestFailingMigration(c *check.C) {
 		return nil
 	})
 	c.Assert(err, check.IsNil)
-	err = Run()
+	err = Run(&buf, false)
 	c.Assert(err, check.NotNil)
 	c.Assert(err.Error(), check.Equals, "something went wrong")
 	c.Assert(runs, check.HasLen, 0)
-	err = Run()
+	err = Run(&buf, false)
 	c.Assert(err, check.IsNil)
 	c.Assert(runs, check.DeepEquals, []string{"mig1", "mig2"})
 }
 
+func (s *Suite) TestRunDryMode(c *check.C) {
+	expected := `Running "migration1"... OK
+Running "migration2"... OK
+Running "migration3"... OK
+`
+	var buf bytes.Buffer
+	var runs []string
+	var mFunc = func(name string) MigrateFunc {
+		return func() error {
+			runs = append(runs, name)
+			return nil
+		}
+	}
+	err := Register("migration1", mFunc("migration1"))
+	c.Assert(err, check.IsNil)
+	err = Register("migration2", mFunc("migration2"))
+	c.Assert(err, check.IsNil)
+	err = Register("migration3", mFunc("migration3"))
+	c.Assert(err, check.IsNil)
+	err = Run(&buf, true)
+	c.Assert(err, check.IsNil)
+	c.Assert(runs, check.HasLen, 0)
+	c.Assert(buf.String(), check.Equals, expected)
+}
+
 func (s *Suite) TestRegisterDuplicate(c *check.C) {
 	err := Register("migration1", nil)
 	c.Assert(err, check.IsNil)