add: unit and integration testing

app/node_modules/@jridgewell/sourcemap-codec/src/vlq.ts

@@ -0,0 +1,51 @@
+import type { StringReader, StringWriter } from './strings';
+
+export const comma = ','.charCodeAt(0);
+export const semicolon = ';'.charCodeAt(0);
+
+const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
+const intToChar = new Uint8Array(64); // 64 possible chars.
+const charToInt = new Uint8Array(128); // z is 122 in ASCII
+
+for (let i = 0; i < chars.length; i++) {
+  const c = chars.charCodeAt(i);
+  intToChar[i] = c;
+  charToInt[c] = i;
+}
+
+export function decodeInteger(reader: StringReader): number {
+  let value = 0;
+  let shift = 0;
+  let integer = 0;
+
+  do {
+    const c = reader.next();
+    integer = charToInt[c];
+    value |= (integer & 31) << shift;
+    shift += 5;
+  } while (integer & 32);
+
+  return value;
+}
+
+export function decodeSign(num: number): number {
+  return num & 1 ? -0x80000000 | -(num >>> 1) : num >>> 1;
+}
+
+export function encodeInteger(builder: StringWriter, num: number) {
+  do {
+    let clamped = num & 0b011111;
+    num >>>= 5;
+    if (num > 0) clamped |= 0b100000;
+    builder.write(intToChar[clamped]);
+  } while (num > 0);
+}
+
+export function encodeSign(num: number): number {
+  return num < 0 ? (-num << 1) | 1 : num << 1;
+}
+
+export function hasMoreVlq(reader: StringReader, max: number) {
+  if (reader.pos >= max) return false;
+  return reader.peek() !== comma;
+}