fixed eslint issue of ArrayByCache and ArrayByCache.test.ts

.eslintignore

@@ -44,8 +44,6 @@ src/Explorer/DataSamples/ContainerSampleGenerator.test.ts
 src/Explorer/DataSamples/ContainerSampleGenerator.ts
 src/Explorer/DataSamples/DataSamplesUtil.test.ts
 src/Explorer/DataSamples/DataSamplesUtil.ts
-src/Explorer/Graph/GraphExplorerComponent/ArraysByKeyCache.test.ts
-src/Explorer/Graph/GraphExplorerComponent/ArraysByKeyCache.ts
 src/Explorer/Graph/GraphExplorerComponent/D3ForceGraph.test.ts
 src/Explorer/Graph/GraphExplorerComponent/D3ForceGraph.ts
 src/Explorer/Graph/GraphExplorerComponent/EdgeInfoCache.ts

src/Explorer/Graph/GraphExplorerComponent/ArraysByKeyCache.test.ts

@@ -6,7 +6,7 @@ describe("Cache arrays by key", () => {
     const key = "key";
     cache.insert(key, 1, 0);
     cache.clear();
-    expect(cache.retrieve(key, 0, 1)).toBe(null);
+    expect(cache.retrieve(key, 0, 1)).toBe(undefined);
   });
 
   it("should invalidate oldest key to keep cache size under maximum", () => {
@@ -21,7 +21,7 @@ describe("Cache arrays by key", () => {
     cache.insert(key1, 2, 4);
 
     expect(cache.retrieve(key1, 0, 3)).toEqual([0, 2, 4]);
-    expect(cache.retrieve(key2, 1, 1)).toEqual(null);
+    expect(cache.retrieve(key2, 1, 1)).toEqual(undefined);
   });
 
   it("should cache and retrieve cached page within boundaries", () => {
@@ -39,7 +39,7 @@ describe("Cache arrays by key", () => {
     const key = "key";
     cache.insert(key, 0, 0);
     cache.insert(key, 1, 1);
-    expect(cache.retrieve(key, 2, 1)).toEqual(null);
+    expect(cache.retrieve(key, 2, 1)).toEqual(undefined);
   });
 
   it("should not retrieve cached page overlapping boundaries", () => {
@@ -48,7 +48,7 @@ describe("Cache arrays by key", () => {
     cache.insert(key, 0, 0);
     cache.insert(key, 1, 1);
     cache.insert(key, 2, 2);
-    expect(cache.retrieve(key, 2, 4)).toEqual(null);
+    expect(cache.retrieve(key, 2, 4)).toEqual(undefined);
   });
 
   it("should not insert non-contiguous element", () => {
@@ -57,7 +57,7 @@ describe("Cache arrays by key", () => {
     cache.insert(key, 0, 0);
     cache.insert(key, 1, 1);
     cache.insert(key, 3, 3);
-    expect(cache.retrieve(key, 3, 1)).toEqual(null);
+    expect(cache.retrieve(key, 3, 1)).toEqual(undefined);
   });
 
   it("should cache multiple keys", () => {

src/Explorer/Graph/GraphExplorerComponent/ArraysByKeyCache.ts

@@ -61,12 +61,12 @@ export class ArraysByKeyCache<T> {
    * @param pageSize
    */
   public retrieve(key: string, startIndex: number, pageSize: number): T[] | null {
-    if (!this.cache.hasOwnProperty(key)) {
-      return null;
+    if (!Object.prototype.hasOwnProperty.call(this.cache, key)) {
+      return undefined;
     }
     const elements = this.cache[key];
     if (startIndex + pageSize > elements.length) {
-      return null;
+      return undefined;
     }
 
     return elements.slice(startIndex, startIndex + pageSize);