fix(loaders[i].loaders): add descriptive error message (#126)

Author: le0nik

src/properties/module/index.js

@@ -27,6 +27,12 @@ const LOADER_EXCLUDE_FORBIDDEN = oneLine`
   which might inadvertently slow your build down. Use \`include\` instead. (loader-prefer-include)
 `
 
+const LOADER_IN_LOADERS_MESSAGE = oneLine`
+  at position {{pos}} must be a String or an Object with properties:
+  "loader": (String, required),
+  "query": (Object, optional)
+`
+
 const conditionSchema = Joi.array().items([
   Joi.string(),
   Joi.object().type(RegExp),
@@ -46,7 +52,13 @@ const loaderSchemaFn = ({ rules }) => {
         loader: Joi.string().required(),
         query: Joi.object(),
       })
-    ),
+    ).options({
+      language: {
+        array: {
+          includes: LOADER_IN_LOADERS_MESSAGE,
+        },
+      },
+    }),
   })
     .xor('loaders', 'loader')
     .nand('loaders', 'query')

src/properties/module/index.test.js

@@ -1,4 +1,8 @@
-import schemaFn, { CONDITION_MESSAGE, LOADERS_QUERY_MESSAGE } from './index'
+import schemaFn, {
+  CONDITION_MESSAGE,
+  LOADERS_QUERY_MESSAGE,
+  LOADER_IN_LOADERS_MESSAGE,
+} from './index'
 import { allValid, allInvalid } from '../../../test/utils'
 
 const validModuleConfigs = [
@@ -96,7 +100,7 @@ const invalidModuleConfigs = [
       ],
     },
     error: {
-      message: '"loaders" at position 0 does not match any of the allowed types',
+      message: LOADER_IN_LOADERS_MESSAGE,
       path: 'loaders.0.loaders.0',
     },
   },
@@ -177,7 +181,7 @@ const invalidModuleConfigs = [
       }],
     },
     error: {
-      message: '"loaders" at position 0 does not match any of the allowed types',
+      message: LOADER_IN_LOADERS_MESSAGE,
       path: 'loaders.0.loaders.0',
     },
   },
@@ -193,7 +197,7 @@ const invalidModuleConfigs = [
       }],
     },
     error: {
-      message: '"loaders" at position 0 does not match any of the allowed types',
+      message: LOADER_IN_LOADERS_MESSAGE,
       path: 'loaders.0.loaders.0',
     },
   },