schemadiff: more index expression validations (tests only) (vitessio#17483)

Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>

Author: shlomi-noach

go/test/endtoend/onlineddl/revert/onlineddl_revert_test.go

@@ -259,6 +259,11 @@ func testRevertible(t *testing.T) {
 			toSchema:              `id int primary key, i2 int default null`,
 			removedUniqueKeyNames: `i1_uidx`,
 		},
+		{
+			name:       "removed expression unique key, skipped",
+			fromSchema: `id int primary key, i1 int default null, unique key idx1 ((id + 1))`,
+			toSchema:   `id int primary key, i2 int default null`,
+		},
 		{
 			name:                  "expanding unique key removes unique constraint",
 			fromSchema:            `id int primary key, i1 int default null, unique key i1_uidx(i1)`,

go/vt/schemadiff/onlineddl_test.go

@@ -937,6 +937,11 @@ func TestRevertible(t *testing.T) {
 			fromSchema: "id int, primary key (id), key idx1 ((id + 1))",
 			toSchema:   "id int, primary key (id), key idx2 ((id + 2))",
 		},
+		{
+			name:       "remove unique index with expression, add another, skip both",
+			fromSchema: "id int, i int, primary key (id), unique key idx1 ((id + 1))",
+			toSchema:   "id int, i int, primary key (id), unique key idx2 ((i  + 2))",
+		},
 	}
 
 	var (

go/vt/schemadiff/table_test.go

@@ -2582,6 +2582,24 @@ func TestValidate(t *testing.T) {
 			alter: "alter table t add key idx2 ((id + 2))",
 			to:    "create table t (id int, primary key (id), key idx1 ((id + 1)), key idx2 ((id + 2)))",
 		},
+		{
+			name:  "key with multicolumn expression",
+			from:  "create table t (id int, i int, primary key (id), key idx1 ((id + 1), (i + 2)))",
+			alter: "alter table t add key idx2 ((id + 2))",
+			to:    "create table t (id int, i int, primary key (id), key idx1 ((id + 1), (i + 2)), key idx2 ((id + 2)))",
+		},
+		{
+			name:      "key with expression and unknown columns",
+			from:      "create table t (id int, i int, primary key (id), key idx1 ((id + 1), (i + 2)))",
+			alter:     "alter table t add key idx2 ((i2 + 2))",
+			expectErr: &InvalidColumnInKeyError{Table: "t", Column: "i2", Key: "idx2"},
+		},
+		{
+			name:      "drop column used in expression",
+			from:      "create table t (id int, i int, primary key (id), key idx1 ((id + 1), (i + 2)))",
+			alter:     "alter table t drop column i",
+			expectErr: &InvalidColumnInKeyError{Table: "t", Column: "i", Key: "idx1"},
+		},
 		// partitions
 		{
 			name:      "drop column used by partitions",