refactor 404 error handling for getMi as per letter operations

Author: RossFaulds171

internal/datastore/src/errors/mi-not-found-error.ts

@@ -0,0 +1,12 @@
+/**
+ * Error thrown when management information is not found in the database.
+ */
+export default class MiNotFoundError extends Error {
+  constructor(
+    public readonly supplierId: string,
+    public readonly miId: string,
+  ) {
+    super(`Management information not found: supplierId=${supplierId}, miId=${miId}`);
+    this.name = "MiNotFoundError";
+  }
+}

internal/datastore/src/index.ts

@@ -7,3 +7,4 @@ export { default as LetterQueueRepository } from "./letter-queue-repository";
 export { default as DBHealthcheck } from "./healthcheck";
 export { default as LetterAlreadyExistsError } from "./errors/letter-already-exists-error";
 export { default as LetterNotFoundError } from "./errors/letter-not-found-error";
+export { default as MiNotFoundError } from "./errors/mi-not-found-error";

lambdas/api-handler/src/services/__tests__/mi-operations.test.ts

@@ -1,5 +1,7 @@
 import { IncomingMI } from "../../contracts/mi";
 import { getMI, postMI } from "../mi-operations";
+import MiNotFoundError from "@internal/datastore/src/errors/mi-not-found-error";
+
 
 describe("postMI function", () => {
   const incomingMi: IncomingMI = {
@@ -61,4 +63,26 @@ describe("postMI function", () => {
       },
     });
   });
+
+  it("should throw notFoundError when letter does not exist", async () => {
+    const mockRepo = {
+      getMI: jest
+        .fn()
+        .mockRejectedValue(new MiNotFoundError("miId1", "supplier1")),
+    };
+
+    await expect(
+      getMI("miId1", "supplier1", mockRepo as any),
+    ).rejects.toThrow("No resource found with that ID");
+  });
+
+  it("should throw unexpected error", async () => {
+    const mockRepo = {
+      getMI: jest.fn().mockRejectedValue(new Error("unexpected error")),
+    };
+
+    await expect(
+      getMI("miId1", "supplier1", mockRepo as any),
+    ).rejects.toThrow("unexpected error");
+  });
 });

lambdas/api-handler/src/services/letter-operations.ts

@@ -74,7 +74,7 @@ export const getLetterById = async (
     letter = await letterRepo.getLetterById(supplierId, letterId);
   } catch (error) {
     if (error instanceof LetterNotFoundError) {
-      throw new NotFoundError(ApiErrorDetail.NotFoundLetterId);
+      throw new NotFoundError(ApiErrorDetail.NotFoundId);
     }
     throw error;
   }
@@ -98,7 +98,7 @@ export const getLetterDataUrl = async (
     );
   } catch (error) {
     if (error instanceof LetterNotFoundError) {
-      throw new NotFoundError(ApiErrorDetail.NotFoundLetterId);
+      throw new NotFoundError(ApiErrorDetail.NotFoundId);
     }
     throw error;
   }

lambdas/api-handler/src/services/mi-operations.ts

@@ -3,13 +3,7 @@ import { GetMIResponse, IncomingMI, PostMIResponse } from "../contracts/mi";
 import { mapToGetMIResponse, mapToPostMIResponse } from "../mappers/mi-mapper";
 import { ApiErrorDetail } from "../contracts/errors";
 import NotFoundError from "../errors/not-found-error";
-
-function isNotFoundError(error: any) {
-  return (
-    error instanceof Error &&
-    /^Management Information with id \w+ not found for supplier \w+$/.test(error.message)
-  );
-}
+import MiNotFoundError from "@internal/datastore/src/errors/letter-not-found-error";
 
 export const postMI = async (
   incomingMi: IncomingMI,
@@ -28,7 +22,7 @@ export const getMI = async (
   try {
     mi = await miRepo.getMI(miId, supplierId);
   } catch (error) {
-    if (isNotFoundError(error)) {
+    if (error instanceof MiNotFoundError) {
       throw new NotFoundError(ApiErrorDetail.NotFoundId);
     }
     throw error;