page path defaults to '/' (gatsbyjs#3325)

* page path defaults to '/'

* Add test

Author: luczaki114

packages/gatsby/src/redux/__tests__/pages.js

@@ -21,6 +21,18 @@ describe(`Add pages`, () => {
     expect(state).toMatchSnapshot()
   })
 
+  it(`adds an initial forward slash if the user doesn't`, () => {
+    const action = actions.createPage(
+      {
+        path: `hi/`,
+        component: `/whatever/index.js`,
+      },
+      { id: `test`, name: `test` }
+    )
+    const state = reducer(undefined, action)
+    expect(state[0].path).toEqual(`/hi/`)
+  })
+
   it(`allows you to add pages with context`, () => {
     const action = actions.createPage(
       {

packages/gatsby/src/redux/actions.js

@@ -133,6 +133,11 @@ actions.createPage = (page: PageInput, plugin?: Plugin, traceId?: string) => {
     updatedAt: Date.now(),
   }
 
+  // If the path doesn't have an initial forward slash, add it.
+  if (internalPage.path[0] !== `/`) {
+    internalPage.path = `/${internalPage.path}`
+  }
+
   const result = Joi.validate(internalPage, joiSchemas.pageSchema)
   if (result.error) {
     console.log(chalk.blue.bgYellow(`The upserted page didn't pass validation`))
@@ -141,11 +146,6 @@ actions.createPage = (page: PageInput, plugin?: Plugin, traceId?: string) => {
     return null
   }
 
-  // If the path doesn't have an initial forward slash, add it.
-  if (internalPage.path[0] !== `/`) {
-    internalPage.path = `/${internalPage.path}`
-  }
-
   return {
     type: `CREATE_PAGE`,
     plugin,