Add empty-string and partial-match tests

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: BrianY315

practice-tdd/count.test.js

@@ -17,6 +17,13 @@ test("should count multiple occurrences of a character", () => {
   expect(count).toEqual(5);
 });
 
+test("should count occurrences when the character appears within the string", () => {
+  const str = "hello";
+  const char = "l";
+  const count = countChar(str, char);
+  expect(count).toEqual(2);
+});
+
 // Scenario: No Occurrences
 // Given the input string `str`,
 // And a character `char` that does not exist within `str`.
@@ -29,3 +36,10 @@ test("should return 0 when the character does not occur", () => {
   const count = countChar(str, char);
   expect(count).toEqual(0);
 });
+
+test("should return 0 when the string is empty", () => {
+  const str = "";
+  const char = "z";
+  const count = countChar(str, char);
+  expect(count).toEqual(0);
+});

practice-tdd/repeat-str.test.js

@@ -14,6 +14,7 @@ test("should repeat the string count times", () => {
   const count = 3;
   const repeatedStr = repeatStr(str, count);
   expect(repeatedStr).toEqual("hellohellohello");
+  expect(repeatStr("", count)).toEqual("");
 });
 
 // Case: handle count of 1:
@@ -26,6 +27,7 @@ test("should return the original string when count is 1", () => {
   const count = 1;
   const repeatedStr = repeatStr(str, count);
   expect(repeatedStr).toEqual("hello");
+  expect(repeatStr("", count)).toEqual("");
 });
 
 // Case: Handle count of 0:
@@ -38,6 +40,7 @@ test("should return an empty string when count is 0", () => {
   const count = 0;
   const repeatedStr = repeatStr(str, count);
   expect(repeatedStr).toEqual("");
+  expect(repeatStr("", count)).toEqual("");
 });
 
 // Case: Handle negative count:
@@ -49,4 +52,5 @@ test("should throw an error when count is negative", () => {
   const str = "hello";
   const count = -1;
   expect(() => repeatStr(str, count)).toThrow();
+  expect(() => repeatStr("", count)).toThrow();
 });