chore(refactor): split up and add tests for core functionality

src/auth/getTokens.ts

@@ -0,0 +1,40 @@
+import {
+  AuthConfig,
+  isAccessTokenExpiring,
+  isRefreshTokenExpiring,
+  hasTokenExpired
+} from '@sasjs/utils'
+import { RequestClient } from '../request/RequestClient'
+import { refreshTokens } from './refreshTokens'
+
+/**
+ * Returns the auth configuration, refreshing the tokens if necessary.
+ * @param requestClient - the pre-configured HTTP request client
+ * @param authConfig - an object containing a client ID, secret, access token and refresh token
+ */
+export async function getTokens(
+  requestClient: RequestClient,
+  authConfig: AuthConfig
+): Promise<AuthConfig> {
+  const logger = process.logger || console
+  let { access_token, refresh_token, client, secret } = authConfig
+  if (
+    isAccessTokenExpiring(access_token) ||
+    isRefreshTokenExpiring(refresh_token)
+  ) {
+    if (hasTokenExpired(refresh_token)) {
+      const error =
+        'Unable to obtain new access token. Your refresh token has expired.'
+      logger.error(error)
+      throw new Error(error)
+    }
+    logger.info('Refreshing access and refresh tokens.')
+    ;({ access_token, refresh_token } = await refreshTokens(
+      requestClient,
+      client,
+      secret,
+      refresh_token
+    ))
+  }
+  return { access_token, refresh_token, client, secret }
+}