TDD: wrote count.test.js with scenarios before implementating countChar

Author: Eugenie-A

Sprint-3/2-practice-tdd/count.test.js

@@ -22,3 +22,62 @@ test("should count multiple occurrences of a character", () => {
 // And a character `char` that does not exist within `str`.
 // When the function is called with these inputs,
 // Then it should return 0, indicating that no occurrences of `char` were found.
+test("should return 0 when character does not appear in string", () => {
+  expect(countChar("hello", "x")).toEqual(0);
+  expect(countChar("banana", "z")).toEqual(0);
+  // empty string
+  expect(countChar("", "a")).toEqual(0);
+});
+
+// Scenario: Single Occurence
+// Given a string where `char` appears exactly once,
+// When countChar is called,
+// Then it should return 1.
+test("should return 1 when character appears exactly once", () => {
+  expect(countChar("hello", "h")).toEqual(1);
+  expect(countChar("banana", "n")).toEqual(1);
+  expect(countChar("xyz", "y")).toEqual(1);
+});
+
+// Scenario: Case Sensitivity
+// Given a string with mixed case letters, 
+// When countChar is called with a specific case,
+// Then it should count only exact matches (case-sensitive).
+test("should be case-sensitive when counting characters", () => {
+  expect(countChar("Hello", "H")).toEqual(1);
+  expect(countChar("Hello", "h")).toEqual(0);
+  expect(countChar("AAAaaa", "A")).toEqual(3);
+  expect(countChar("AAAaaa", "a")).toEqual(3);
+});
+
+// Scenario: Special Characters/Symbols
+// Given a string containing punctuation or emojis,
+// When counting a special character,
+// Then it should correctly identify and count it.
+test("should count special characters and emojis", () => {
+  expect(countChar("hello!!!", "!")).toEqual(3);
+  expect(countChar("smile 😊😊😊", "😊")).toEqual(3);
+});
+
+// Scenario: Longer Mixed String
+// Given a longer string with various characters and spaces,
+// When counting different characters,
+// Then it should return the correct count for each.
+test("should count correctly in longer mixed string", () => {
+  const str = "i am writing some jest tests right now";
+  // some, now
+  expect(countChar(str, "o")).toEqual(2);
+  // some, jest, tests
+  expect(countChar(str, "e")).toEqual(3);
+  // spaces
+  expect(countChar(str, " ")).toEqual(7);
+});
+
+// Scenario: Single Character String
+// Given a string containing only one character,
+// When countChar is called,
+// Then it should correctly handle matching or non-matching cases.
+test("should handle single character strings", () => {
+  expect(countChar("a", "a")).toEqual(1);
+  expect(countChar("b", "a")).toEqual(0);
+});