Test DropView node

Signed-off-by: Alejandro García Montoro <alejandro.garciamontoro@gmail.com>

Author: agarciamontoro

sql/plan/drop_view_test.go

@@ -0,0 +1,94 @@
+package plan
+
+import (
+	"testing"
+
+	"github.com/src-d/go-mysql-server/memory"
+	"github.com/src-d/go-mysql-server/sql"
+	"github.com/src-d/go-mysql-server/sql/expression"
+
+	"github.com/stretchr/testify/require"
+)
+
+// Generates a database with a single table called mytable and a catalog with
+// the view that is also returned. The context returned is the one used to
+// create the view.
+func mockData(require *require.Assertions) (sql.Database, *sql.Catalog, *sql.Context, sql.View) {
+	table := memory.NewTable("mytable", sql.Schema{
+		{Name: "i", Source: "mytable", Type: sql.Int32},
+		{Name: "s", Source: "mytable", Type: sql.Text},
+	})
+
+	db := memory.NewDatabase("db")
+	db.AddTable("db", table)
+
+	catalog := sql.NewCatalog()
+	catalog.AddDatabase(db)
+
+	subqueryAlias := NewSubqueryAlias("myview",
+		NewProject(
+			[]sql.Expression{
+				expression.NewGetFieldWithTable(1, sql.Int32, table.Name(), "i", true),
+			},
+			NewUnresolvedTable("dual", ""),
+		),
+	)
+
+	createView := NewCreateView(db, subqueryAlias.Name(), nil, subqueryAlias, false)
+	createView.Catalog = catalog
+
+	ctx := sql.NewEmptyContext()
+
+	_, err := createView.RowIter(ctx)
+	require.NoError(err)
+
+	return db, catalog, ctx, createView.View()
+}
+
+// Tests that DropView works as expected and that the view is dropped in
+// the catalog when RowIter is called, regardless of the value of ifExists
+func TestDropExistingView(t *testing.T) {
+	require := require.New(t)
+
+	test := func(ifExists bool) {
+		db, catalog, ctx, view := mockData(require)
+
+		singleDropView := NewSingleDropView(db, view.Name())
+		dropView := NewDropView([]sql.Node{singleDropView}, ifExists)
+		dropView.Catalog = catalog
+
+		_, err := dropView.RowIter(ctx)
+		require.NoError(err)
+
+		require.False(catalog.ViewRegistry.Exists(db.Name(), view.Name()))
+	}
+
+	test(false)
+	test(true)
+}
+
+// Tests that DropView errors when trying to delete a non-existing view if and
+// only if the flag ifExists is set to false
+func TestDropNonExistingView(t *testing.T) {
+	require := require.New(t)
+
+	test := func(ifExists bool) error {
+		db, catalog, ctx, view := mockData(require)
+
+		singleDropView := NewSingleDropView(db, "non-existing-view")
+		dropView := NewDropView([]sql.Node{singleDropView}, ifExists)
+		dropView.Catalog = catalog
+
+		_, err := dropView.RowIter(ctx)
+
+		require.True(catalog.ViewRegistry.Exists(db.Name(), view.Name()))
+
+		return err
+	}
+
+	err := test(true)
+	require.NoError(err)
+
+	err = test(false)
+	require.Error(err)
+}