feat: add upperCase function (#402)

* feat(upperCase): Add upperCase function

* Add upperCase benchmark

* Added english docs

benchmarks/performance/upperCase.bench.ts

@@ -0,0 +1,28 @@
+import { bench, describe } from 'vitest';
+import { upperCase as upperCaseToolkit } from 'es-toolkit';
+import { upperCase as upperCaseLodash } from 'lodash';
+
+describe('upperCase', () => {
+  describe('short string', () => {
+    bench('es-toolkit/upperCase', () => {
+      const str = 'camelCase';
+      upperCaseToolkit(str);
+    });
+
+    bench('lodash/upperCase', () => {
+      const str = 'camelCase';
+      upperCaseLodash(str);
+    });
+  });
+
+  describe('long string', () => {
+    const LONG_STR = 'camelCaseLongString'.repeat(1000);
+    bench('es-toolkit/upperCase', () => {
+      upperCaseToolkit(LONG_STR);
+    });
+
+    bench('lodash/upperCase', () => {
+      upperCaseLodash(LONG_STR);
+    });
+  });
+});

docs/reference/string/upperCase.md

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+# upperCase
+
+Converts a string to upper case.
+
+Upper case is the naming convention in which each word is written in uppercase and separated by an space ( ) character. For example, `UPPER CASE`.
+
+## Signature
+
+```typescript
+function upperCase(str: string): string;
+```
+
+### Parameters
+
+- `str` (`string`): The string that is to be changed to upper case.
+
+### Returns
+
+(`string`) The converted string to upper case.
+
+## Examples
+
+```typescript
+import { upperCase } from 'es-toolkit/string';
+
+upperCase('camelCase'); // returns 'CAMEL CASE'
+upperCase('some whitespace'); // returns 'SOME WHITESPACE'
+upperCase('hyphen-text'); // returns 'HYPHEN TEXT'
+upperCase('HTTPRequest'); // returns 'HTTP REQUEST'
+```

src/string/index.ts

@@ -1,6 +1,7 @@
 export { camelCase } from './camelCase.ts';
 export { snakeCase } from './snakeCase.ts';
 export { kebabCase } from './kebabCase.ts';
+export { upperCase } from './upperCase.ts';
 export { lowerCase } from './lowerCase.ts';
 export { startCase } from './startCase.ts';
 export { capitalize } from './capitalize.ts';

src/string/upperCase.spec.ts

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+import { describe, it, expect } from 'vitest';
+import { upperCase } from './upperCase';
+
+describe('upperCase', () => {
+  it('should change camel case to upper case', async () => {
+    expect(upperCase('camelCase')).toEqual('CAMEL CASE');
+  });
+
+  it('should change space to space', async () => {
+    expect(upperCase('some whitespace')).toEqual('SOME WHITESPACE');
+  });
+
+  it('should change hyphen to space', async () => {
+    expect(upperCase('hyphen-text')).toEqual('HYPHEN TEXT');
+  });
+
+  it('should change Acronyms to small letter', async () => {
+    expect(upperCase('HTTPRequest')).toEqual('HTTP REQUEST');
+  });
+
+  it('should handle leading and trailing whitespace', async () => {
+    expect(upperCase('    leading and trailing whitespace')).toEqual('LEADING AND TRAILING WHITESPACE');
+  });
+
+  it('should handle special characters correctly', async () => {
+    expect(upperCase('special@characters!')).toEqual('SPECIAL CHARACTERS');
+  });
+
+  it('should handle strings that are already in upper case', async () => {
+    expect(upperCase('upper_case')).toEqual('UPPER CASE');
+  });
+
+  it('should work with an empty string', async () => {
+    expect(upperCase('')).toEqual('');
+  });
+
+  it('should work with screaming snake case', async () => {
+    expect(upperCase('FOO_BAR')).toEqual('FOO BAR');
+  });
+});

src/string/upperCase.ts

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+import { getWords } from './_internal/getWords.ts';
+
+/**
+ * Converts a string to upper case.
+ *
+ * Upper case is the naming convention in which each word is written in uppercase and separated by an space ( ) character.
+ *
+ * @param {string} str - The string that is to be changed to upper case.
+ * @returns {string} - The converted string to upper case.
+ *
+ * @example
+ * const convertedStr1 = upperCase('camelCase') // returns 'CAMEL CASE'
+ * const convertedStr2 = upperCase('some whitespace') // returns 'SOME WHITESPACE'
+ * const convertedStr3 = upperCase('hyphen-text') // returns 'HYPHEN TEXT'
+ * const convertedStr4 = upperCase('HTTPRequest') // returns 'HTTP REQUEST'
+ */
+export const upperCase = (str: string): string => {
+  const words = getWords(str);
+  return words.map(word => word.toUpperCase()).join(' ');
+};