Use JSON for plan tests

go/vt/vtgate/engine/plan.go

@@ -17,6 +17,7 @@ limitations under the License.
 package engine
 
 import (
+	"bytes"
 	"encoding/json"
 	"sync/atomic"
 	"time"
@@ -98,5 +99,14 @@ func (p *Plan) MarshalJSON() ([]byte, error) {
 		Errors:       atomic.LoadUint64(&p.Errors),
 		TablesUsed:   p.TablesUsed,
 	}
-	return json.Marshal(marshalPlan)
+
+	b := new(bytes.Buffer)
+	enc := json.NewEncoder(b)
+	enc.SetEscapeHTML(false)
+	err := enc.Encode(marshalPlan)
+	if err != nil {
+		return nil, err
+	}
+
+	return b.Bytes(), nil
 }

go/vt/vtgate/engine/plan_description.go

@@ -161,12 +161,11 @@ func addMap(input map[string]any, buf *bytes.Buffer) error {
 
 func marshalAdd(prepend string, buf *bytes.Buffer, name string, obj any) error {
 	buf.WriteString(prepend + `"` + name + `":`)
-	b, err := json.Marshal(obj)
-	if err != nil {
-		return err
-	}
-	buf.Write(b)
-	return nil
+
+	enc := json.NewEncoder(buf)
+	enc.SetEscapeHTML(false)
+
+	return enc.Encode(obj)
 }
 
 // PrimitiveToPlanDescription transforms a primitive tree into a corresponding PlanDescription tree

go/vt/vtgate/planbuilder/collations_test.go

@@ -40,7 +40,7 @@ type collationTestCase struct {
 
 func (tc *collationTestCase) run(t *testing.T) {
 	vschemaWrapper := &vschemaWrapper{
-		v:             loadSchema(t, "schema_test.json", false),
+		v:             loadSchema(t, "vschemas/schema.json", false),
 		sysVarEnabled: true,
 		version:       Gen4,
 	}