feat: emit errors as part of fetchFromMultipleSources

src/libs/fetchFromMultipleSources.spec.ts

@@ -9,35 +9,56 @@ describe("fetchFromMultipleSources", () => {
     );
   });
 
-  it("has promises, returns first one with value", async () => {
-    const actual = await fetchFromMultipleSources<number>([
+  it("has promises with valid responses, returns first one with value", async () => {
+    const { result } = await fetchFromMultipleSources<number>([
       () => Promise.resolve(undefined),
       () => Promise.resolve(null),
       () => Promise.reject(),
       () => Promise.resolve(2),
       () => Promise.resolve(3),
     ]);
-    const expected = 2;
 
-    expect(actual).toEqual(expected);
+    expect(result).toEqual(2);
   });
 
-  it("has promises, no valid responses, returns null", async () => {
-    const actual = await fetchFromMultipleSources<number>([
+  it("has promises with valid responses, contains no errors", async () => {
+    const { errors } = await fetchFromMultipleSources<number>([
+      () => Promise.resolve(undefined),
       () => Promise.resolve(null),
       () => Promise.reject(),
-      () => Promise.resolve(undefined),
+      () => Promise.resolve(2),
+      () => Promise.resolve(3),
     ]);
-    const expected = null;
 
-    expect(actual).toBe(expected);
+    expect(errors).toBeNull();
   });
 
-  it("has promises, has cached value, returns cached value", async () => {
-    const actual = await fetchFromMultipleSources<number>(
+  it("has promises with no valid responses, returns null", async () => {
+    const { result } = await fetchFromMultipleSources<number>([
+      () => Promise.resolve(null),
+      () => Promise.reject("error"),
+      () => Promise.resolve(undefined),
+    ]);
+
+    expect(result).toBeNull();
+  });
+
+  it("has promises with no valid responses, contains error", async () => {
+    const { errors } = await fetchFromMultipleSources<number>([
+      () => Promise.resolve(null),
+      () => Promise.reject("error"),
+      () => Promise.reject(new Error("error")),
+      () => Promise.resolve(undefined),
+    ]);
+
+    expect(errors).toEqual(["error", new Error("error")]);
+  });
+
+  it("has promises but cache has value, returns cached value", async () => {
+    const { result } = await fetchFromMultipleSources<number>(
       [
         () => Promise.resolve(null),
-        () => Promise.reject(),
+        () => Promise.reject("error"),
         () => Promise.resolve(undefined),
       ],
       {
@@ -45,9 +66,24 @@ describe("fetchFromMultipleSources", () => {
         saveInCache: async () => {},
       },
     );
-    const expected = -1;
 
-    expect(actual).toBe(expected);
+    expect(result).toEqual(-1);
+  });
+
+  it("has promises but cache has value, contains no errors", async () => {
+    const { errors } = await fetchFromMultipleSources<number>(
+      [
+        () => Promise.resolve(null),
+        () => Promise.reject("error"),
+        () => Promise.resolve(undefined),
+      ],
+      {
+        fetchFromCache: () => Promise.resolve(-1),
+        saveInCache: async () => {},
+      },
+    );
+
+    expect(errors).toBeNull();
   });
 
   it("has promises, no cached value, no valid response, should not save in cache", async () => {
@@ -65,9 +101,8 @@ describe("fetchFromMultipleSources", () => {
         },
       },
     );
-    const expected = undefined;
 
-    expect(actual).toBe(expected);
+    expect(actual).toBeUndefined();
   });
 
   it("has promises, no cached value, has valid response, should save in cache", async () => {
@@ -89,4 +124,20 @@ describe("fetchFromMultipleSources", () => {
 
     expect(actual).toBe(expected);
   });
+
+  it("has promises, no cached value, has valid response, value that was cached is returned", async () => {
+    const { result } = await fetchFromMultipleSources(
+      [
+        () => Promise.resolve(null),
+        () => Promise.reject(),
+        () => Promise.resolve(3),
+      ],
+      {
+        fetchFromCache: () => Promise.resolve(null),
+        saveInCache: async (value) => {},
+      },
+    );
+
+    expect(result).toBe(3);
+  });
 });