feat: option to ensure variable is within the list of values (#1827)

requires.go

@@ -1,6 +1,8 @@
 package task
 
 import (
+	"slices"
+
 	"github.com/go-task/task/v3/errors"
 	"github.com/go-task/task/v3/taskfile/ast"
 )
@@ -16,9 +18,19 @@ func (e *Executor) areTaskRequiredVarsSet(t *ast.Task, call *ast.Call) error {
 	}
 
 	var missingVars []string
+	var notAllowedValuesVars []errors.NotAllowedVar
 	for _, requiredVar := range t.Requires.Vars {
-		if !vars.Exists(requiredVar) {
-			missingVars = append(missingVars, requiredVar)
+		value, isString := vars.Get(requiredVar.Name).Value.(string)
+		if !vars.Exists(requiredVar.Name) {
+			missingVars = append(missingVars, requiredVar.Name)
+		} else {
+			if isString && requiredVar.Enum != nil && !slices.Contains(requiredVar.Enum, value) {
+				notAllowedValuesVars = append(notAllowedValuesVars, errors.NotAllowedVar{
+					Value: value,
+					Enum:  requiredVar.Enum,
+					Name:  requiredVar.Name,
+				})
+			}
 		}
 	}
 
@@ -29,5 +41,12 @@ func (e *Executor) areTaskRequiredVarsSet(t *ast.Task, call *ast.Call) error {
 		}
 	}
 
+	if len(notAllowedValuesVars) > 0 {
+		return &errors.TaskNotAllowedVars{
+			TaskName:       t.Name(),
+			NotAllowedVars: notAllowedValuesVars,
+		}
+	}
+
 	return nil
 }