fix: enforce precedence for specific migrations (#533)

closes #532

migration_info.go

@@ -37,6 +37,10 @@ func (mfs Migrations) Len() int {
 }
 
 func (mfs Migrations) Less(i, j int) bool {
+	if mfs[i].Version == mfs[j].Version {
+		// force "all" to the back
+		return mfs[i].DBType != "all"
+	}
 	return mfs[i].Version < mfs[j].Version
 }
 

migration_info_test.go

@@ -0,0 +1,50 @@
+package pop
+
+import (
+	"github.com/stretchr/testify/assert"
+	"sort"
+	"testing"
+)
+
+func TestSortingMigrations(t *testing.T) {
+	t.Run("case=enforces precedence for specific migrations", func(t *testing.T) {
+		migrations := Migrations{
+			{
+				Version: "1",
+				DBType:  "all",
+			},
+			{
+				Version: "1",
+				DBType:  "postgres",
+			},
+			{
+				Version: "2",
+				DBType:  "cockroach",
+			},
+			{
+				Version: "2",
+				DBType:  "all",
+			},
+			{
+				Version: "3",
+				DBType:  "all",
+			},
+			{
+				Version: "3",
+				DBType:  "mysql",
+			},
+		}
+		expectedOrder := Migrations{
+			migrations[1],
+			migrations[0],
+			migrations[2],
+			migrations[3],
+			migrations[5],
+			migrations[4],
+		}
+
+		sort.Sort(migrations)
+
+		assert.Equal(t, expectedOrder, migrations)
+	})
+}