fix: Fixed to treat a single value as an array if it is an array sche…

…ma (#49)

coercion.ts

@@ -63,11 +63,40 @@ function coerce<T extends GenericSchema | GenericSchemaAsync>(
   return pipe(unknown, vTransform(transformFunction), type);
 }
 
+/**
+ * Helpers for coercing array value
+ * Modify the value only if it's an array, otherwise return the value as-is
+ */
+function coerceArray<T extends GenericSchema | GenericSchemaAsync>(type: T) {
+  // `expects` is required to generate error messages for `TupleSchema`, so it is passed to `UnkonwSchema` for coercion.
+  const unknown = { ...valibotUnknown(), expects: type.expects };
+  const transformFunction = (output: unknown): unknown => {
+    if (Array.isArray(output)) {
+      return output;
+    }
+
+    if (
+      typeof output === "undefined" ||
+      typeof coerceFile(coerceString(output)) === "undefined"
+    ) {
+      return [];
+    }
+
+    return [output];
+  };
+
+  if (type.async) {
+    return pipeAsync(unknown, vTransform(transformFunction), type);
+  }
+
+  return pipe(unknown, vTransform(transformFunction), type);
+}
+
 /**
  * Helpers for coercing file
  * Modify the value only if it's a file, otherwise return the value as-is
  */
-export function coerceFile(file: unknown) {
+function coerceFile(file: unknown) {
   if (
     typeof File !== "undefined" &&
     file instanceof File &&
@@ -205,7 +234,7 @@ export function enableTypeCoercion<
       };
       return {
         coerced: false,
-        schema: generateReturnSchema(type, arraySchema),
+        schema: generateReturnSchema(type, coerceArray(arraySchema)),
       };
     }
     case "optional":

tests/coercion/schema/array.test.ts

@@ -7,11 +7,18 @@ describe("array", () => {
   test("should pass only arrays", () => {
     const schema = object({ select: array(string()) });
     const formData = createFormData("select", "1");
+    const outputForNonArray = parseWithValibot(formData, { schema });
+
+    expect(outputForNonArray).toMatchObject({
+      status: "success",
+      value: { select: ["1"] },
+    });
+
     formData.append("select", "2");
     formData.append("select", "3");
-    const output = parseWithValibot(formData, { schema });
+    const outputForArray = parseWithValibot(formData, { schema });
 
-    expect(output).toMatchObject({
+    expect(outputForArray).toMatchObject({
       status: "success",
       value: { select: ["1", "2", "3"] },
     });