Add support for comparing timestamps with separators by falling back to string comparison when VersionInt() of two migration steps are equal.

Author: Lars Moastuen

migrate.go

@@ -81,7 +81,7 @@ type Migration struct {
 
 func (m Migration) Less(other *Migration) bool {
 	switch {
-	case m.isNumeric() && other.isNumeric():
+	case m.isNumeric() && other.isNumeric() && m.VersionInt()-other.VersionInt() != 0:
 		return m.VersionInt() < other.VersionInt()
 	case m.isNumeric() && !other.isNumeric():
 		return true

migrate_test.go

@@ -359,3 +359,20 @@ func (s *SqliteMigrateSuite) TestPlanMigrationWithHoles(c *C) {
 	c.Assert(plannedMigrations[2].Migration.Id, Equals, "2")
 	c.Assert(plannedMigrations[2].Queries[0], Equals, down)
 }
+
+func (s *SqliteMigrateSuite) TestLessTwoNumeric(c *C) {
+	c.Assert((Migration{Id: "1"}).Less(&Migration{Id: "2"}), Equals, true)      // 1 less than 2
+	c.Assert((Migration{Id: "2"}).Less(&Migration{Id: "1"}), Equals, false)     // 2 not less than 1
+	c.Assert((Migration{Id: "1"}).Less(&Migration{Id: "a"}), Equals, true)      // 1 less than a
+	c.Assert((Migration{Id: "a"}).Less(&Migration{Id: "1"}), Equals, false)     // a not less than 1
+	c.Assert((Migration{Id: "a"}).Less(&Migration{Id: "a"}), Equals, false)     // a not less than a
+	c.Assert((Migration{Id: "1-a"}).Less(&Migration{Id: "1-b"}), Equals, true)  // 1-a less than 1-b
+	c.Assert((Migration{Id: "1-b"}).Less(&Migration{Id: "1-a"}), Equals, false) // 1-b not less than 1-a
+	// 20160126_1100 less than 20160126_1200
+	c.Assert((Migration{Id: "20160126_1100"}).
+		Less(&Migration{Id: "20160126_1200"}), Equals, true)
+	// 20160126_1200 not less than 20160126_1100
+	c.Assert((Migration{Id: "20160126_1200"}).
+		Less(&Migration{Id: "20160126_1100"}), Equals, false)
+
+}