fix(json-ot): 🐛 make compose() function pass fuzzer tests

Author: streamich

src/json-ot/types/ot-string/StringType.ts

@@ -204,7 +204,7 @@ export const compose = (op1: StringTypeOp, op2: StringTypeOp): StringTypeOp => {
         } else if (remaining >= (length1 - off1)) {
           const end = off2 + (length1 - off1);
           switch (typeof comp1) {
-            case 'number': append(op3, isReversible ? [comp2[0].substring(off2, end)] : -length1); break;
+            case 'number': append(op3, isReversible ? [comp2[0].substring(off2, end)] : -(length1 - off1)); break;
             case 'string': {
               off2 += (length1 - off1);
               break;

src/json-ot/types/ot-string/__tests__/StringOtFuzzer.ts

@@ -5,7 +5,7 @@ import {StringTypeOp} from "../types";
 
 export class StringOtFuzzer extends Fuzzer {
   genString(): string {
-    return RandomJson.genString(2);
+    return RandomJson.genString(20);
   }
 
   genOp(str: string): StringTypeOp {

src/json-ot/types/ot-string/__tests__/StringType.spec.ts

@@ -106,6 +106,7 @@ describe('compose()', () => {
     ['fuzzer bug #2', 'Ai', [['A'], '#', -1], [-1], ''],
     ['fuzzer bug #3', 'M}', ['!y1'], ["'/*s", 2, ',/@', -2, ['}']], "'/*s!y,/@"],
     ['fuzzer bug #4', '8sL', [-2, 'w', ['L']], [['w']], ''],
+    ['fuzzer bug #5', '%V=', [2, ';'], ['3O"', 1, 'J', -2], '3O"%J='],
   ];
 
   describe('can compose', () => {

src/json-ot/types/ot-string/__tests__/fuzzer.compose.spec.ts

@@ -4,7 +4,7 @@ import {StringOtFuzzer} from './StringOtFuzzer';
 const fuzzer = new StringOtFuzzer();
 
 test('works', () => {
-  for (let i = 0; i < 100000; i++) {
+  for (let i = 0; i < 10000; i++) {
     const str1 = fuzzer.genString();
     const op1 = fuzzer.genOp(str1);
     const str2 = apply(str1, op1);