Issue #6 Write tests for CollectionUtils

Added tests for collection-utils methods replaceelementAt and length

Author: brandongregoryscott

src/utilities/collection-utils.test.ts

@@ -3,6 +3,10 @@ import { CollectionUtils } from "./collection-utils";
 import { ResultRecord } from "../view-models/result-record";
 
 describe("CollectionUtils", () => {
+    // -----------------------------------------------------------------------------------------
+    // #region hasValues
+    // -----------------------------------------------------------------------------------------
+
     describe("hasValues", () => {
         test("when collections param is an array and has elements, it returns true", (): void => {
             // Arrange
@@ -108,7 +112,13 @@ describe("CollectionUtils", () => {
             // Assert
             expect(result).toBeTrue();
         });
-    }); // end hasValues
+    });
+
+    // #endregion hasValues
+
+    // -----------------------------------------------------------------------------------------
+    // #region isEmpty
+    // -----------------------------------------------------------------------------------------
 
     describe("isEmpty", () => {
         test(`when collections param is an array and has elements, it returns false`, (): void => {
@@ -213,7 +223,13 @@ describe("CollectionUtils", () => {
             // Assert
             expect(result).toBeFalse();
         });
-    }); // end isEmpty()
+    });
+
+    // #endregion isEmpty
+
+    // -----------------------------------------------------------------------------------------
+    // #region isNotEmpty
+    // -----------------------------------------------------------------------------------------
 
     describe("#isNotEmpty", () => {
         test(`when collections param is an array and has elements, it returns true`, (): void => {
@@ -320,7 +336,54 @@ describe("CollectionUtils", () => {
             // Assert
             expect(result).toBeTrue();
         });
-    }); // end isNotEmpty
+    });
+
+    // #endregion isNotEmpty
+
+    // -----------------------------------------------------------------------------------------
+    // #region length
+    // -----------------------------------------------------------------------------------------
+
+    describe("#length", () => {
+        test(`when collections param is an array and has elements, it returns the length`, (): void => {
+            // Arrange
+            const array = ["test", "test"];
+
+            // Act
+            const result = CollectionUtils.length(array);
+
+            // Assert
+            expect(result).toBe(array.length);
+        });
+
+        test(`when collections param is null, it returns -1`, (): void => {
+            // Arrange
+            const array = null;
+
+            // Act
+            const result = CollectionUtils.length(array);
+
+            // Assert
+            expect(result).toBe(-1);
+        });
+
+        test(`when collections param is a list and has elements, it returns the length`, (): void => {
+            // Arrange
+            const list = List(["test","test"]);
+
+            // Act
+            const result = CollectionUtils.length(list);
+
+            // Assert
+            expect(result).toBe(list.size);
+        });
+    })
+
+    // #endregion length
+
+    // -----------------------------------------------------------------------------------------
+    // #region equalsBy
+    // -----------------------------------------------------------------------------------------
 
     describe("#equalsBy", () => {
         type TestType = { id: number };
@@ -386,6 +449,12 @@ describe("CollectionUtils", () => {
         });
     });
 
+    // #endregion equalsBy
+
+    // -----------------------------------------------------------------------------------------
+    // #region removeElementAt
+    // -----------------------------------------------------------------------------------------
+
     describe("#removeElementAt", () => {
         it("when index i < 0, returns source array", () => {
             // Arrange
@@ -425,6 +494,12 @@ describe("CollectionUtils", () => {
         });
     });
 
+    // #endregion removeElementAt
+
+    // -----------------------------------------------------------------------------------------
+    // #region replaceElementAt
+    // -----------------------------------------------------------------------------------------
+
     describe("#replaceElementAt", () => {
         it("Replaces element at specified index and returns a new array", () => {
             // Arrange
@@ -435,12 +510,58 @@ describe("CollectionUtils", () => {
             const result = CollectionUtils.replaceElementAt(arr, 1, "replaced");
 
             // Assert
-            const equals = CollectionUtils.equalsBy(
-                (s: string) => s,
-                result,
-                expected
-            );
-            expect(equals).toBe(true);
+            expect(result).not.toBe(arr);
+            expect(result).toStrictEqual(expected);
         });
+
+        it("When source array has no values it, then returns the source array", () => {
+            // Arrange
+            const arr = [];
+
+            // Act
+            const result = CollectionUtils.replaceElementAt(arr, 1, "replaced");
+
+            // Assert
+            expect(result).toBe(arr);
+        })
+
+        it("When source array has 1 item it, then returns new array with 1 item", () => {
+            // Arrange
+            const arr = ["test"];
+            const expected = ["replaced-test"];
+
+            // Act
+            const result = CollectionUtils.replaceElementAt(arr, 2, "replaced-test");
+
+            // Assert
+            expect(result).not.toBe(arr);
+            expect(result).toStrictEqual(expected);
+        })
+
+        it("When index is last element of source it, then returns new array with value at the end", () => {
+            // Arrange
+            const arr = ["zero", "one", "two", "three", "four"];
+            const expected = ["zero", "one", "two", "three", "replaced"];
+
+            // Act
+            const result = CollectionUtils.replaceElementAt(arr, 4, "replaced");
+
+            // Assert
+            expect(result).not.toBe(arr);
+            expect(result).toStrictEqual(expected);
+        })
+
+        it("When index i < 0, then returns the source array", () => {
+            // Arrange
+            const arr = ["zero", "one", "two", "three", "four"];
+
+            // Act
+            const result = CollectionUtils.replaceElementAt(arr, -1, "replaced");
+
+            // Assert
+            expect(result).toBe(arr);
+        })
     });
+
+    // #endregion replaceElementAt
 });

src/utilities/collection-utils.ts

@@ -155,7 +155,8 @@ const _removeElementAt = <T>(source: Array<T>, index: number): Array<T> => {
 
 /**
  * Returns a NEW array with the element at the specified index
- * replaced with the specified value. Since it returns a new array,
+ * replaced with the specified value if the index provided is
+ * greater than zero, else it returns the source array. Since it returns a new array,
  * this can be safely used as the value for a React.SetStateAction
  * i.e. setMyArray(CollectionUtils.replaceElementAt(myArray, index, newValue));
  * @param source
@@ -167,7 +168,7 @@ const _replaceElementAt = <T>(
     index: number,
     value: T
 ): Array<T> => {
-    if (source.length === 0) {
+    if (source.length === 0 || index < 0) {
         return source;
     }
     if (source.length === 1) {