add testcase for decodeText module (#144)

* add testcase for decodeText module

* add strict remove and remove some comment

* add test case with utf16 char

test/decode-text.test.js

@@ -0,0 +1,33 @@
+'use strict'
+
+const { test } = require('tap')
+const decodeText = require('../lib/utils/decodeText')
+
+test('decodeText', t => {
+  const testCases = [
+    { description: 'UTF-8 encoding', text: Buffer.from('Hello, World!', 'utf8'), initialCharset: 'utf8', outputCharset: 'utf8', expected: 'Hello, World!' },
+    { description: 'UTF-8 encoding empty', text: Buffer.from('', 'utf8'), initialCharset: 'utf8', outputCharset: 'utf8', expected: '' },
+    { description: 'Latin1 encoding', text: Buffer.from('Hello, World!', 'latin1'), initialCharset: 'latin1', outputCharset: 'latin1', expected: 'Hello, World!' },
+    { description: 'Latin1 encoding empty', text: Buffer.from('', 'latin1'), initialCharset: 'latin1', outputCharset: 'latin1', expected: '' },
+    { description: 'UTF-16LE encoding', text: Buffer.from('Hello, World!', 'utf16le'), initialCharset: 'utf16le', outputCharset: 'utf16le', expected: 'Hello, World!' },
+    { description: 'UTF-16LE encoding with special char', text: Buffer.from('Hello, World! 🌍🚀', 'utf16le'), initialCharset: 'utf16le', outputCharset: 'utf16le', expected: 'Hello, World! 🌍🚀' },
+    { description: 'UTF-8 to UTF-16LE encoding', text: 'Hello, World!', initialCharset: 'utf16le', outputCharset: 'utf16le', expected: 'Hello, World!' },
+    { description: 'UTF-16LE encoding empty', text: Buffer.from('', 'utf16le'), initialCharset: 'utf16le', outputCharset: 'utf16le', expected: '' },
+    { description: 'Base64 encoding', text: Buffer.from('Hello, World!').toString('base64'), initialCharset: 'base64', outputCharset: 'base64', expected: 'SGVsbG8sIFdvcmxkIQ==' },
+    { description: 'UTF-8 to Base64 encoding', text: 'Hello, World!', initialCharset: 'utf8', outputCharset: 'base64', expected: 'SGVsbG8sIFdvcmxkIQ==' },
+    { description: 'Base64 encoding empty', text: Buffer.from('', 'utf8'), initialCharset: 'utf8', outputCharset: 'base64', expected: '' },
+    { description: 'UTF8 to base64', text: Buffer.from('Hello, World!', 'utf-8'), initialCharset: 'utf8', outputCharset: 'base64', expected: 'SGVsbG8sIFdvcmxkIQ==' },
+    { description: 'Unknown', text: 'Hello, World!', initialCharset: 'utf8', outputCharset: 'other', expected: 'Hello, World!' },
+    { description: 'Unknown empty', text: Buffer.from('', 'utf8'), initialCharset: 'utf8', outputCharset: 'other', expected: '' },
+    { description: 'Unknown', text: 'Hello, World!', initialCharset: 'utf8', outputCharset: 'utf-8', expected: 'Hello, World!' }
+  ]
+
+  t.plan(testCases.length)
+
+  testCases.forEach((c, index) => {
+    t.test(c.description, t => {
+      t.plan(1)
+      t.equal(decodeText(c.text, c.initialCharset, c.outputCharset), c.expected, `Test case ${index + 1}`)
+    })
+  })
+})