fix(spanner/spannertest): fix handling of NULL with LIKE operator (#2982

)

spanner/spannertest/db_eval.go

@@ -141,6 +141,13 @@ func (ec evalContext) evalBoolExpr(be spansql.BoolExpr) (bool, error) {
 		case spansql.Ne:
 			return compareVals(lhs, rhs) != 0, nil
 		case spansql.Like, spansql.NotLike:
+			if lhs == nil || rhs == nil {
+				// Either operand being NULL should result in NULL.
+				// TODO: Perhaps evalBoolExpr should be merged with evalExpr,
+				// and boolean coercion should happen at the top-most level
+				// so NULLs can be correctly transported.
+				return false, nil
+			}
 			left, ok := lhs.(string)
 			if !ok {
 				// TODO: byte works here too?

spanner/spannertest/integration_test.go

@@ -409,6 +409,7 @@ func TestIntegration_ReadsAndQueries(t *testing.T) {
 		"PlayerStats",
 		"JoinA",
 		"JoinB",
+		"SomeStrings",
 	}
 	for _, table := range allTables {
 		dropTable(t, adminClient, table)
@@ -594,6 +595,8 @@ func TestIntegration_ReadsAndQueries(t *testing.T) {
 		// JoinA and JoinB are "A" and "B" from https://cloud.google.com/spanner/docs/query-syntax#join_types.
 		`CREATE TABLE JoinA ( w INT64, x STRING(MAX) ) PRIMARY KEY (w, x)`,
 		`CREATE TABLE JoinB ( y INT64, z STRING(MAX) ) PRIMARY KEY (y, z)`,
+		// Some other test tables.
+		`CREATE TABLE SomeStrings ( i INT64, str STRING(MAX) ) PRIMARY KEY (i)`,
 	)
 	if err != nil {
 		t.Fatalf("Creating sample tables: %v", err)
@@ -614,6 +617,11 @@ func TestIntegration_ReadsAndQueries(t *testing.T) {
 		spanner.Insert("JoinB", []string{"y", "z"}, []interface{}{3, "m"}),
 		spanner.Insert("JoinB", []string{"y", "z"}, []interface{}{3, "n"}),
 		spanner.Insert("JoinB", []string{"y", "z"}, []interface{}{4, "p"}),
+
+		spanner.Insert("SomeStrings", []string{"i", "str"}, []interface{}{0, "afoo"}),
+		spanner.Insert("SomeStrings", []string{"i", "str"}, []interface{}{1, "abar"}),
+		spanner.Insert("SomeStrings", []string{"i", "str"}, []interface{}{2, nil}),
+		spanner.Insert("SomeStrings", []string{"i", "str"}, []interface{}{3, "bbar"}),
 	})
 	if err != nil {
 		t.Fatalf("Inserting sample data: %v", err)
@@ -874,6 +882,24 @@ func TestIntegration_ReadsAndQueries(t *testing.T) {
 				{int64(1)},
 			},
 		},
+		// Regression TEST for mishandling NULLs with LIKE operator.
+		{
+			`SELECT i, str FROM SomeStrings WHERE str LIKE "%bar"`,
+			nil,
+			[][]interface{}{
+				// Does not include [0, "afoo"] or [2, nil].
+				{int64(1), "abar"},
+				{int64(3), "bbar"},
+			},
+		},
+		{
+			`SELECT i, str FROM SomeStrings WHERE str NOT LIKE "%bar"`,
+			nil,
+			[][]interface{}{
+				// Does not include [1, "abar"], [2, nil] or [3, "bbar"].
+				{int64(0), "afoo"},
+			},
+		},
 	}
 	for _, test := range tests {
 		stmt := spanner.NewStatement(test.q)