Initial work, copied from the Shopify provider

framework/saleor/auth/use-signup.tsx

@@ -0,0 +1,70 @@
+import { useCallback } from 'react'
+import type { MutationHook } from '@commerce/utils/types'
+import { CommerceError, ValidationError } from '@commerce/utils/errors'
+import useSignup, { UseSignup } from '@commerce/auth/use-signup'
+import useCustomer from '../customer/use-customer'
+import {
+  CustomerCreateInput,
+  Mutation,
+  MutationCustomerCreateArgs,
+} from '../schema'
+
+import { customerCreateMutation } from '../utils/mutations'
+import { handleAutomaticLogin, throwUserErrors } from '../utils'
+
+export default useSignup as UseSignup<typeof handler>
+
+export const handler: MutationHook<
+  null,
+  {},
+  CustomerCreateInput,
+  CustomerCreateInput
+> = {
+  fetchOptions: {
+    query: customerCreateMutation,
+  },
+  async fetcher({
+    input: { firstName, lastName, email, password },
+    options,
+    fetch,
+  }) {
+    if (!(firstName && lastName && email && password)) {
+      throw new CommerceError({
+        message:
+          'A first name, last name, email and password are required to signup',
+      })
+    }
+
+    const { customerCreate } = await fetch<
+      Mutation,
+      MutationCustomerCreateArgs
+    >({
+      ...options,
+      variables: {
+        input: {
+          firstName,
+          lastName,
+          email,
+          password,
+        },
+      },
+    })
+
+    throwUserErrors(customerCreate?.customerUserErrors)
+    await handleAutomaticLogin(fetch, { email, password })
+
+    return null
+  },
+  useHook: ({ fetch }) => () => {
+    const { revalidate } = useCustomer()
+
+    return useCallback(
+      async function signup(input) {
+        const data = await fetch({ input })
+        await revalidate()
+        return data
+      },
+      [fetch, revalidate]
+    )
+  },
+}