Fix Yaml/Syml stringify with keys longer than 1024 chars

Author: elado

packages/yarnpkg-parsers/sources/syml.ts

@@ -91,11 +91,21 @@ function stringifyValue(value: any, indentLevel: number, newLineIfObject: boolea
         ? indent
         : ``;
 
-      if (stringifiedValue.startsWith(`\n`)) {
-        return `${recordIndentation}${stringifiedKey}:${stringifiedValue}`;
-      } else {
-        return `${recordIndentation}${stringifiedKey}: ${stringifiedValue}`;
-      }
+
+      let keyPart: string;
+      let valuePart: string;
+
+      // Yaml 1.2 spec says that keys over 1024 characters need to be prefixed with ? and the : goes in a new line
+      if (stringifiedKey.length > 1024)
+        keyPart = `? ${stringifiedKey}\n:`;
+      else keyPart = `${stringifiedKey}:`;
+
+      if (stringifiedValue.startsWith(`\n`))
+        valuePart = stringifiedValue;
+      else valuePart = ` ${stringifiedValue}`;
+
+
+      return `${recordIndentation}${keyPart}${valuePart}`;
     }).join(indentLevel === 0 ? `\n` : ``) || `\n`;
 
     if (!newLineIfObject) {

packages/yarnpkg-parsers/tests/syml.test.js

@@ -1,4 +1,4 @@
-import {parseSyml} from '@yarnpkg/parsers';
+import {parseSyml, stringifySyml} from '@yarnpkg/parsers';
 
 describe(`Syml parser`, () => {
   it(`shouldn't confuse old-style values with new-style keys`, () => {
@@ -21,13 +21,25 @@ describe(`Syml parser`, () => {
 
   it(`should merge duplicates`, () => {
     expect(
-      parseSyml(`    
+      parseSyml(`
       "lodash@npm:^4.17.20":
         version: 4.17.20
-      
+
       "lodash@npm:^4.17.20":
         version: 4.17.20
       `),
     ).toEqual({'lodash@npm:^4.17.20': {version: `4.17.20`}});
   });
 });
+
+describe(`Syml stringifyer`, () => {
+  it(`stringifies an object`, () => {
+    expect(stringifySyml({foo: {bar: `true`, baz: `quux`}})).toEqual(`foo:\n  bar: true\n  baz: quux\n`);
+  });
+
+  it(`stringifies an object with a long key with yaml 1.2 spec`, () => {
+    const longKey = `a`.repeat(1025); // long key is a string of length > 1024
+    expect(stringifySyml({[longKey]: {bar: `true`, baz: `quux`}})).toEqual(`? ${longKey}\n:\n  bar: true\n  baz: quux\n`);
+    expect(stringifySyml({[longKey]: {[longKey]: `quux`, baz: `quux`}})).toEqual(`? ${longKey}\n:\n  ? ${longKey}\n: quux\n  baz: quux\n`);
+  });
+});