refactor: rewrites "sortTransactions" to TypeScript

packages/dredd/lib/sortTransactions.ts

@@ -0,0 +1,61 @@
+import { RESTMethod, Transaction } from './general';
+
+const sortedMethods: RESTMethod[] = [
+  RESTMethod.CONNECT,
+  RESTMethod.OPTIONS,
+  RESTMethod.POST,
+  RESTMethod.GET,
+  RESTMethod.HEAD,
+  RESTMethod.PUT,
+  RESTMethod.PATCH,
+  RESTMethod.DELETE,
+  RESTMethod.TRACE,
+];
+
+// Often, API description is arranged with a sequence of methods that lends
+// itself to understanding by the human reading the documentation.
+//
+// However, the sequence of methods may not be appropriate for the machine
+// reading the documentation in order to test the API.
+//
+// By sorting the transactions by their methods, it is possible to ensure that
+// objects are created before they are read, updated, or deleted.
+export default function sortTransactions(
+  transactions: Transaction[],
+): Transaction[] {
+  // Convert the list of transactions into a list of tuples
+  // that hold each trasnaction index and details.
+  const tempTransactions: Array<[number, Transaction]> = transactions.map(
+    (transaction, index) => [index, transaction],
+  );
+
+  tempTransactions.sort(
+    ([leftIndex, leftTransaction], [rightIndex, rightTransaction]) => {
+      const methodIndexA = sortedMethods.indexOf(
+        leftTransaction.request.method,
+      );
+      const methodIndexB = sortedMethods.indexOf(
+        rightTransaction.request.method,
+      );
+
+      // Sort transactions according to the transaction's request method
+      if (methodIndexA < methodIndexB) {
+        return -1;
+      }
+
+      if (methodIndexA > methodIndexB) {
+        return 1;
+      }
+
+      // In case two transactions' request methods are the same,
+      // preserve the original order of those transactions
+      return leftIndex - rightIndex;
+    },
+  );
+
+  const cleanTransactions = tempTransactions.map(
+    ([_, transaction]) => transaction,
+  );
+
+  return cleanTransactions;
+}