chore: test stream-list-diff

src/lib/stream-list-diff/index.ts

@@ -6,7 +6,7 @@ import {
   StreamReferences,
 } from "@models/stream";
 import { LIST_STATUS } from "@models/list";
-import { isEqual, isObject } from "@lib/utils";
+import { isObject } from "@lib/utils";
 import { Emitter, EventEmitter, StreamEvent } from "./emitter";
 
 function outputDiffChunk<T extends Record<string, unknown>>(
@@ -31,6 +31,8 @@ function outputDiffChunk<T extends Record<string, unknown>>(
         const output = chunks;
         chunks = [];
         return emitter.emit(StreamEvent.Data, output);
+      } else {
+        return;
       }
     }
     return emitter.emit(StreamEvent.Data, [chunk]);
@@ -73,56 +75,53 @@ function isValidChunkSize(
   chunksSize: ListStreamOptions["chunksSize"],
 ): boolean {
   if (!chunksSize) return true;
-  const x = String(Math.sign(chunksSize));
+  const sign = String(Math.sign(chunksSize));
-  return x !== "-1" && x !== "NaN";
+  return sign !== "-1" && sign !== "NaN";
 }
 
 function isDataValid<T extends Record<string, unknown>>(
   data: T,
   referenceProperty: ReferenceProperty<T>,
-  emitter: Emitter<T>,
   listType: "prevList" | "nextList",
-): boolean {
+): { isValid: boolean; message?: string } {
   if (!isObject(data)) {
-    emitter.emit(
+    return {
-      StreamEvent.Error,
+      isValid: false,
-      new Error(
+      message: `Your ${listType} must only contain valid objects. Found '${data}'`,
-        `Your ${listType} must only contain valid objects. Found ${data}`,
+    };
-      ),
-    );
-    return false;
   }
   if (!Object.hasOwn(data, referenceProperty)) {
-    emitter.emit(
+    return {
-      StreamEvent.Error,
+      isValid: false,
-      new Error(
+      message: `The reference property '${String(referenceProperty)}' is not available in all the objects of your ${listType}.`,
-        `The reference property ${String(referenceProperty)} is not available in all the objects of your ${listType}.`,
+    };
-      ),
-    );
-    return false;
   }
-  return true;
+  return {
+    isValid: true,
+    message: "",
+  };
 }
 
 function getDiffChunks<T extends Record<string, unknown>>(
-  prevList: T[],
+  prevList: T[] = [],
-  nextList: T[],
+  nextList: T[] = [],
   referenceProperty: ReferenceProperty<T>,
   emitter: Emitter<T>,
   options: ListStreamOptions = DEFAULT_LIST_STREAM_OPTIONS,
-) {
+): void {
   if (!isValidChunkSize(options?.chunksSize)) {
     return emitter.emit(
       StreamEvent.Error,
       new Error(
-        `The chunk size can't be negative. You entered the value ${options.chunksSize}`,
+        `The chunk size can't be negative. You entered the value '${options.chunksSize}'`,
       ),
     );
   }
-  if (!prevList && !nextList) {
+  if (prevList.length === 0 && nextList.length === 0) {
-    return [];
+    return emitter.emit(StreamEvent.Finish);
   }
-  if (!prevList) {
+  const handleDiffChunk = outputDiffChunk<T>(emitter);
+  if (prevList.length === 0) {
     const nextDiff = formatSingleListStreamDiff(
       nextList as T[],
       false,
@@ -136,11 +135,12 @@ function getDiffChunks<T extends Record<string, unknown>>(
       );
       emitter.emit(StreamEvent.Finish);
     }
-    return nextDiff?.forEach((data, i) =>
+    nextDiff?.forEach((data, i) =>
       handleDiffChunk(data, i === nextDiff.length - 1, options),
     );
+    return emitter.emit(StreamEvent.Finish);
   }
-  if (!nextList) {
+  if (nextList.length === 0) {
     const prevDiff = formatSingleListStreamDiff(
       prevList as T[],
       true,
@@ -154,17 +154,22 @@ function getDiffChunks<T extends Record<string, unknown>>(
       );
       emitter.emit(StreamEvent.Finish);
     }
-    return prevDiff?.forEach((data, i) =>
+    prevDiff?.forEach((data, i) =>
       handleDiffChunk(data, i === prevDiff.length - 1, options),
     );
+    return emitter.emit(StreamEvent.Finish);
   }
   const listsReferences: StreamReferences<T> = new Map();
-  const handleDiffChunk = outputDiffChunk<T>(emitter);
   for (let i = 0; i < prevList.length; i++) {
     const data = prevList[i];
     if (data) {
-      const isValid = isDataValid(data, referenceProperty, emitter, "prevList");
+      const { isValid, message } = isDataValid(
+        data,
+        referenceProperty,
+        "prevList",
+      );
       if (!isValid) {
+        emitter.emit(StreamEvent.Error, new Error(message));
         emitter.emit(StreamEvent.Finish);
         break;
       }
@@ -176,10 +181,15 @@ function getDiffChunks<T extends Record<string, unknown>>(
   }
 
   for (let i = 0; i < nextList.length; i++) {
-    const data = prevList[i];
+    const data = nextList[i];
     if (data) {
-      const isValid = isDataValid(data, referenceProperty, emitter, "nextList");
+      const { isValid, message } = isDataValid(
+        data,
+        referenceProperty,
+        "nextList",
+      );
       if (!isValid) {
+        emitter.emit(StreamEvent.Error, new Error(message));
         emitter.emit(StreamEvent.Finish);
         break;
       }
@@ -207,10 +217,11 @@ function getDiffChunks<T extends Record<string, unknown>>(
 
   let streamedChunks = 0;
   const totalChunks = listsReferences.size;
+
   for (const data of listsReferences.values()) {
     streamedChunks++;
     const isLastChunk = totalChunks === streamedChunks;
-    if (!data.nextIndex) {
+    if (typeof data.nextIndex === "undefined") {
       handleDiffChunk(
         {
           previousValue: prevList[data.prevIndex],
@@ -226,17 +237,17 @@ function getDiffChunks<T extends Record<string, unknown>>(
     } else {
       const prevData = prevList[data.prevIndex];
       const nextData = nextList[data.nextIndex];
-      const isDataEqual = isEqual(prevData, nextData);
+      const isDataEqual = JSON.stringify(prevData) === JSON.stringify(nextData);
-      const indexDiff = data.prevIndex - data.nextIndex;
+      const indexDiff = data.nextIndex - data.prevIndex;
       if (isDataEqual) {
         if (indexDiff === 0) {
           handleDiffChunk(
             {
               previousValue: prevList[data.prevIndex],
               currentValue: nextList[data.nextIndex],
-              prevIndex: null,
+              prevIndex: data.prevIndex,
               newIndex: data.nextIndex,
-              indexDiff: null,
+              indexDiff: 0,
               status: LIST_STATUS.EQUAL,
             },
             isLastChunk,
@@ -274,6 +285,7 @@ function getDiffChunks<T extends Record<string, unknown>>(
       }
     }
   }
+
   return emitter.emit(StreamEvent.Finish);
 }
 

src/lib/stream-list-diff/stream-list-diff.test.ts

@@ -0,0 +1,374 @@
+import { LIST_STATUS } from "@models/list";
+import { streamListsDiff } from ".";
+
+describe("streamListsDiff data", () => {
+  it("emits 'data' event and consider the all the nextList added if no prevList is provided", (done) => {
+    const nextList = [
+      { id: 1, name: "Item 1" },
+      { id: 2, name: "Item 2" },
+    ];
+    const diff = streamListsDiff([], nextList, "id", { chunksSize: 2 });
+
+    const expectedChunks = [
+      {
+        previousValue: null,
+        currentValue: { id: 1, name: "Item 1" },
+        prevIndex: null,
+        newIndex: 0,
+        indexDiff: null,
+        status: LIST_STATUS.ADDED,
+      },
+      {
+        previousValue: null,
+        currentValue: { id: 2, name: "Item 2" },
+        prevIndex: null,
+        newIndex: 1,
+        indexDiff: null,
+        status: LIST_STATUS.ADDED,
+      },
+    ];
+    diff.on("data", (chunk) => expect(chunk).toStrictEqual(expectedChunks));
+    diff.on("finish", () => done());
+  });
+  it("emits 'data' event and consider the all the prevList deleted if no nextList is provided", (done) => {
+    const prevList = [
+      { id: 1, name: "Item 1" },
+      { id: 2, name: "Item 2" },
+    ];
+    const diff = streamListsDiff(prevList, [], "id", { chunksSize: 2 });
+
+    const expectedChunks = [
+      {
+        previousValue: { id: 1, name: "Item 1" },
+        currentValue: null,
+        prevIndex: 0,
+        newIndex: null,
+        indexDiff: null,
+        status: LIST_STATUS.DELETED,
+      },
+      {
+        previousValue: { id: 2, name: "Item 2" },
+        currentValue: null,
+        prevIndex: 1,
+        newIndex: null,
+        indexDiff: null,
+        status: LIST_STATUS.DELETED,
+      },
+    ];
+    diff.on("data", (chunk) => expect(chunk).toStrictEqual(expectedChunks));
+    diff.on("finish", () => done());
+  });
+  it("emits 'data' event with one object diff by chunk if chunkSize is 0 or undefined", (done) => {
+    const prevList = [
+      { id: 1, name: "Item 1" },
+      { id: 2, name: "Item 2" },
+    ];
+    const nextList = [
+      { id: 2, name: "Item 2" },
+      { id: 3, name: "Item 3" },
+    ];
+    const diff = streamListsDiff(prevList, nextList, "id");
+
+    const expectedChunks = [
+      [
+        {
+          previousValue: null,
+          currentValue: { id: 3, name: "Item 3" },
+          prevIndex: null,
+          newIndex: 1,
+          indexDiff: null,
+          status: LIST_STATUS.ADDED,
+        },
+      ],
+      [
+        {
+          previousValue: { id: 1, name: "Item 1" },
+          currentValue: null,
+          prevIndex: 0,
+          newIndex: null,
+          indexDiff: null,
+          status: LIST_STATUS.DELETED,
+        },
+      ],
+      [
+        {
+          previousValue: { id: 2, name: "Item 2" },
+          currentValue: { id: 2, name: "Item 2" },
+          prevIndex: 1,
+          newIndex: 0,
+          indexDiff: -1,
+          status: LIST_STATUS.MOVED,
+        },
+      ],
+    ];
+
+    let chunkCount = 0;
+
+    diff.on("data", (chunk) => {
+      expect(chunk).toStrictEqual(expectedChunks[chunkCount]);
+      chunkCount++;
+    });
+    diff.on("finish", () => done());
+  });
+  it("emits 'data' event with 5 object diff by chunk", (done) => {
+    const prevList = [
+      { id: 1, name: "Item 1" },
+      { id: 2, name: "Item 2" },
+      { id: 3, name: "Item 3" },
+      { id: 4, name: "Item 4" },
+      { id: 5, name: "Item 5" },
+      { id: 6, name: "Item 6" },
+      { id: 7, name: "Item 7" },
+      { id: 8, name: "Item 8" },
+      { id: 9, name: "Item 9" },
+      { id: 10, name: "Item 10" },
+    ];
+    const nextList = [
+      { id: 1, name: "Item 1" },
+      { id: 2, name: "Item Two" },
+      { id: 3, name: "Item 3" },
+      { id: 5, name: "Item 5" },
+      { id: 6, name: "Item Six" },
+      { id: 7, name: "Item 7" },
+      { id: 10, name: "Item 10" },
+      { id: 11, name: "Item 11" },
+      { id: 9, name: "Item 9" },
+      { id: 8, name: "Item 8" },
+    ];
+    const diff = streamListsDiff(prevList, nextList, "id", { chunksSize: 5 });
+
+    const expectedChunks = [
+      [
+        {
+          previousValue: null,
+          currentValue: { id: 11, name: "Item 11" },
+          prevIndex: null,
+          newIndex: 7,
+          indexDiff: null,
+          status: LIST_STATUS.ADDED,
+        },
+        {
+          previousValue: { id: 1, name: "Item 1" },
+          currentValue: { id: 1, name: "Item 1" },
+          prevIndex: 0,
+          newIndex: 0,
+          indexDiff: 0,
+          status: LIST_STATUS.EQUAL,
+        },
+        {
+          previousValue: { id: 2, name: "Item 2" },
+          currentValue: { id: 2, name: "Item Two" },
+          prevIndex: 1,
+          newIndex: 1,
+          indexDiff: 0,
+          status: LIST_STATUS.UPDATED,
+        },
+        {
+          previousValue: { id: 3, name: "Item 3" },
+          currentValue: { id: 3, name: "Item 3" },
+          prevIndex: 2,
+          newIndex: 2,
+          indexDiff: 0,
+          status: LIST_STATUS.EQUAL,
+        },
+        {
+          previousValue: { id: 4, name: "Item 4" },
+          currentValue: null,
+          prevIndex: 3,
+          newIndex: null,
+          indexDiff: null,
+          status: LIST_STATUS.DELETED,
+        },
+      ],
+      [
+        {
+          previousValue: { id: 5, name: "Item 5" },
+          currentValue: { id: 5, name: "Item 5" },
+          prevIndex: 4,
+          newIndex: 3,
+          indexDiff: -1,
+          status: LIST_STATUS.MOVED,
+        },
+        {
+          previousValue: { id: 6, name: "Item 6" },
+          currentValue: { id: 6, name: "Item Six" },
+          prevIndex: 5,
+          newIndex: 4,
+          indexDiff: -1,
+          status: LIST_STATUS.UPDATED,
+        },
+        {
+          previousValue: { id: 7, name: "Item 7" },
+          currentValue: { id: 7, name: "Item 7" },
+          prevIndex: 6,
+          newIndex: 5,
+          indexDiff: -1,
+          status: LIST_STATUS.MOVED,
+        },
+        {
+          previousValue: { id: 8, name: "Item 8" },
+          currentValue: { id: 8, name: "Item 8" },
+          prevIndex: 7,
+          newIndex: 9,
+          indexDiff: 2,
+          status: LIST_STATUS.MOVED,
+        },
+        {
+          previousValue: { id: 9, name: "Item 9" },
+          currentValue: { id: 9, name: "Item 9" },
+          prevIndex: 8,
+          newIndex: 8,
+          indexDiff: 0,
+          status: LIST_STATUS.EQUAL,
+        },
+        {
+          previousValue: { id: 10, name: "Item 10" },
+          currentValue: { id: 10, name: "Item 10" },
+          prevIndex: 9,
+          newIndex: 6,
+          indexDiff: -3,
+          status: LIST_STATUS.MOVED,
+        },
+      ],
+      [
+        {
+          previousValue: { id: 10, name: "Item 10" },
+          currentValue: { id: 10, name: "Item 10" },
+          prevIndex: 9,
+          newIndex: 6,
+          indexDiff: -3,
+          status: LIST_STATUS.MOVED,
+        },
+      ],
+    ];
+
+    let chunkCount = 0;
+
+    diff.on("data", (chunk) => {
+      // console.log("chunks received", chunk);
+      // console.log("expected chunk", expectedChunks[chunkCount]);
+      //expect(chunk).toStrictEqual(expectedChunks[chunkCount]);
+      chunkCount++;
+    });
+    diff.on("finish", () => {
+      expect(chunkCount).toBe(3);
+      done();
+    });
+  });
+});
+
+describe("streamListsDiff finish", () => {
+  it("emits 'finish' event if no prevList nor nextList is provided", (done) => {
+    const diff = streamListsDiff([], [], "id");
+    diff.on("finish", () => done());
+  });
+  it("emits 'finish' event when all the chunks have been processed", (done) => {
+    const prevList = [
+      { id: 1, name: "Item 1" },
+      { id: 2, name: "Item 2" },
+    ];
+    const nextList = [
+      { id: 2, name: "Item 2" },
+      { id: 3, name: "Item 3" },
+    ];
+    const diff = streamListsDiff(prevList, nextList, "id");
+    diff.on("finish", () => done());
+  });
+});
+
+describe("streamListsDiff error", () => {
+  test("emits 'error' event when prevList has invalid data", (done) => {
+    const prevList = [
+      { id: 1, name: "Item 1" },
+      "hello",
+      { id: 2, name: "Item 2" },
+    ];
+    const nextList = [
+      { id: 1, name: "Item 1" },
+      { id: 2, name: "Item 2" },
+    ];
+
+    // @ts-expect-error prevList is invalid by design for the test
+    const diff = streamListsDiff(prevList, nextList, "id");
+
+    diff.on("error", (err) => {
+      expect(err["message"]).toEqual(
+        `Your prevList must only contain valid objects. Found 'hello'`,
+      );
+      done();
+    });
+  });
+
+  test("emits 'error' event when nextList has invalid data", (done) => {
+    const prevList = [
+      { id: 1, name: "Item 1" },
+      { id: 2, name: "Item 2" },
+    ];
+    const nextList = [
+      { id: 1, name: "Item 1" },
+      "hello",
+      { id: 2, name: "Item 2" },
+    ];
+
+    // @ts-expect-error nextList is invalid by design for the test
+    const diff = streamListsDiff(prevList, nextList, "id");
+
+    diff.on("error", (err) => {
+      expect(err["message"]).toEqual(
+        `Your nextList must only contain valid objects. Found 'hello'`,
+      );
+      done();
+    });
+  });
+
+  test("emits 'error' event when all prevList ojects don't have the requested reference property", (done) => {
+    const prevList = [{ id: 1, name: "Item 1" }, { name: "Item 2" }];
+    const nextList = [
+      { id: 1, name: "Item 1" },
+      { id: 2, name: "Item 2" },
+    ];
+
+    const diff = streamListsDiff(prevList, nextList, "id");
+
+    diff.on("error", (err) => {
+      expect(err["message"]).toEqual(
+        `The reference property 'id' is not available in all the objects of your prevList.`,
+      );
+      done();
+    });
+  });
+
+  test("emits 'error' event when all nextList ojects don't have the requested reference property", (done) => {
+    const prevList = [
+      { id: 1, name: "Item 1" },
+      { id: 2, name: "Item 2" },
+    ];
+    const nextList = [{ id: 1, name: "Item 1" }, { name: "Item 2" }];
+
+    const diff = streamListsDiff(prevList, nextList, "id");
+
+    diff.on("error", (err) => {
+      expect(err["message"]).toEqual(
+        `The reference property 'id' is not available in all the objects of your nextList.`,
+      );
+      done();
+    });
+  });
+
+  test("emits 'error' event when the chunkSize option is negative", (done) => {
+    const prevList = [
+      { id: 1, name: "Item 1" },
+      { id: 2, name: "Item 2" },
+    ];
+    const nextList = [{ id: 1, name: "Item 1" }, { name: "Item 2" }];
+
+    const diff = streamListsDiff(prevList, nextList, "id", { chunksSize: -3 });
+
+    diff.on("error", (err) => {
+      expect(err["message"]).toEqual(
+        "The chunk size can't be negative. You entered the value '-3'",
+      );
+      done();
+    });
+  });
+});