Insert new changelog content before the first h2 existing element

... or at the start of the file if none is found

index.js

@@ -7,6 +7,7 @@ const { Plugin } = require('release-it');
 const { format } = require('release-it/lib/util');
 const tmp = require('tmp');
 const execa = require('execa');
+const parse = require('mdast-util-from-markdown');
 
 require('validate-peer-dependencies')(__dirname);
 
@@ -173,7 +174,16 @@ module.exports = class LernaChangelogGeneratorPlugin extends Plugin {
   }
 
   _insertContent(newContent, oldContent) {
-    return newContent + EOL + EOL + oldContent;
+    let insertOffset = this._findInsertOffset(oldContent);
+    let before = oldContent.slice(0, insertOffset);
+    let after = oldContent.slice(insertOffset);
+    return before + newContent + EOL + EOL + after;
+  }
+
+  _findInsertOffset(oldContent) {
+    let ast = parse(oldContent);
+    let firstH2 = ast.children.find((it) => it.type === 'heading' && it.depth === 2);
+    return firstH2 ? firstH2.position.start.offset : 0;
   }
 
   async beforeRelease() {

package.json

@@ -27,6 +27,7 @@
   "dependencies": {
     "execa": "^4.0.3",
     "lerna-changelog": "^1.0.1",
+    "mdast-util-from-markdown": "^0.8.1",
     "tmp": "^0.2.1",
     "validate-peer-dependencies": "^1.0.0",
     "which": "^2.0.2"

test.js

@@ -201,6 +201,22 @@ test('prepends the changelog to the existing file', async (t) => {
   t.is(changelog.toString().trim(), '## v1.0.1 (2020-03-18)\n\nThe changelog\n\nOld contents');
 });
 
+test('adds the changelog after an existing first level heading', async (t) => {
+  let infile = tmp.fileSync().name;
+  let plugin = buildPlugin({ infile });
+  plugin.config.setContext({ git: { tagName: 'v${version}' } });
+
+  fs.writeFileSync(infile, '# Changelog\n\n## v1.0.0\n\nThe old changelog', { encoding: 'utf8' });
+
+  await runTasks(plugin);
+
+  const changelog = fs.readFileSync(infile);
+  t.is(
+    changelog.toString().trim(),
+    '# Changelog\n\n## v1.0.1 (2020-03-18)\n\nThe changelog\n\n## v1.0.0\n\nThe old changelog'
+  );
+});
+
 test('uses launchEditor command', async (t) => {
   let infile = tmp.fileSync().name;
 

yarn.lock

@@ -318,6 +318,13 @@
   dependencies:
     "@types/node" "*"
 
+"@types/mdast@^3.0.0":
+  version "3.0.3"
+  resolved "https://registry.yarnpkg.com/@types/mdast/-/mdast-3.0.3.tgz#2d7d671b1cd1ea3deb306ea75036c2a0407d2deb"
+  integrity sha512-SXPBMnFVQg1s00dlMCc/jCdvPqdE4mXaMMCeRlxLDmTAEoegHT53xKtkDnzDTOcmMHUfcjyf36/YYZ6SxRdnsw==
+  dependencies:
+    "@types/unist" "*"
+
 "@types/minimatch@*":
   version "3.0.3"
   resolved "https://registry.yarnpkg.com/@types/minimatch/-/minimatch-3.0.3.tgz#3dca0e3f33b200fc7d1139c0cd96c1268cadfd9d"
@@ -345,6 +352,11 @@
   dependencies:
     "@types/node" "*"
 
+"@types/unist@*":
+  version "2.0.3"
+  resolved "https://registry.yarnpkg.com/@types/unist/-/unist-2.0.3.tgz#9c088679876f374eb5983f150d4787aa6fb32d7e"
+  integrity sha512-FvUupuM3rlRsRtCN+fDudtmytGO6iHJuuRKS1Ss0pG5z8oX0diNEw94UEL7hgDbpN94rgaK5R7sWm6RrSkZuAQ==
+
 acorn-jsx@^5.2.0:
   version "5.2.0"
   resolved "https://registry.yarnpkg.com/acorn-jsx/-/acorn-jsx-5.2.0.tgz#4c66069173d6fdd68ed85239fc256226182b2ebe"
@@ -731,6 +743,21 @@ chalk@^3.0.0:
     ansi-styles "^4.1.0"
     supports-color "^7.1.0"
 
+character-entities-legacy@^1.0.0:
+  version "1.1.4"
+  resolved "https://registry.yarnpkg.com/character-entities-legacy/-/character-entities-legacy-1.1.4.tgz#94bc1845dce70a5bb9d2ecc748725661293d8fc1"
+  integrity sha512-3Xnr+7ZFS1uxeiUDvV02wQ+QDbc55o97tIV5zHScSPJpcLm/r0DFPcoY3tYRp+VZukxuMeKgXYmsXQHO05zQeA==
+
+character-entities@^1.0.0:
+  version "1.2.4"
+  resolved "https://registry.yarnpkg.com/character-entities/-/character-entities-1.2.4.tgz#e12c3939b7eaf4e5b15e7ad4c5e28e1d48c5b16b"
+  integrity sha512-iBMyeEHxfVnIakwOuDXpVkc54HijNgCyQB2w0VfGQThle6NXn50zU6V/u+LDhxHcDUPojn6Kpga3PTAD8W1bQw==
+
+character-reference-invalid@^1.0.0:
+  version "1.1.4"
+  resolved "https://registry.yarnpkg.com/character-reference-invalid/-/character-reference-invalid-1.1.4.tgz#083329cda0eae272ab3dbbf37e9a382c13af1560"
+  integrity sha512-mKKUkUbhPpQlCOfIuZkvSEgktjPFIsZKRRbC6KWVEMvlzblj3i3asQv5ODsrwt0N3pHAEvjP8KTQPHkp0+6jOg==
+
 chardet@^0.7.0:
   version "0.7.0"
   resolved "https://registry.yarnpkg.com/chardet/-/chardet-0.7.0.tgz#90094849f0937f2eedc2425d0d28a9e5f0cbad9e"
@@ -1021,6 +1048,13 @@ debug@4, debug@4.1.1, debug@^4.0.1, debug@^4.1.0, debug@^4.1.1:
   dependencies:
     ms "^2.1.1"
 
+debug@^4.0.0:
+  version "4.2.0"
+  resolved "https://registry.yarnpkg.com/debug/-/debug-4.2.0.tgz#7f150f93920e94c58f5574c2fd01a3110effe7f1"
+  integrity sha512-IX2ncY78vDTjZMFUdmsvIRFY2Cf4FnD0wRs+nQwJU8Lu99/tPFdb0VybiiMTPe3I6rQmwsqQqRBvxU+bZ/I8sg==
+  dependencies:
+    ms "2.1.2"
+
 decamelize@^1.2.0:
   version "1.2.0"
   resolved "https://registry.yarnpkg.com/decamelize/-/decamelize-1.2.0.tgz#f6534d15148269b20352e7bee26f501f9a191290"
@@ -1899,6 +1933,19 @@ irregular-plurals@^3.2.0:
   resolved "https://registry.yarnpkg.com/irregular-plurals/-/irregular-plurals-3.2.0.tgz#b19c490a0723798db51b235d7e39add44dab0822"
   integrity sha512-YqTdPLfwP7YFN0SsD3QUVCkm9ZG2VzOXv3DOrw5G5mkMbVwptTwVcFv7/C0vOpBmgTxAeTG19XpUs1E522LW9Q==
 
+is-alphabetical@^1.0.0:
+  version "1.0.4"
+  resolved "https://registry.yarnpkg.com/is-alphabetical/-/is-alphabetical-1.0.4.tgz#9e7d6b94916be22153745d184c298cbf986a686d"
+  integrity sha512-DwzsA04LQ10FHTZuL0/grVDk4rFoVH1pjAToYwBrHSxcrBIGQuXrQMtD5U1b0U2XVgKZCTLLP8u2Qxqhy3l2Vg==
+
+is-alphanumerical@^1.0.0:
+  version "1.0.4"
+  resolved "https://registry.yarnpkg.com/is-alphanumerical/-/is-alphanumerical-1.0.4.tgz#7eb9a2431f855f6b1ef1a78e326df515696c4dbf"
+  integrity sha512-UzoZUr+XfVz3t3v4KyGEniVL9BDRoQtY7tOyrRybkVNjDFWyo1yhXNGrrBTQxp3ib9BLAWs7k2YKBQsFRkZG9A==
+  dependencies:
+    is-alphabetical "^1.0.0"
+    is-decimal "^1.0.0"
+
 is-arrayish@^0.2.1:
   version "0.2.1"
   resolved "https://registry.yarnpkg.com/is-arrayish/-/is-arrayish-0.2.1.tgz#77c99840527aa8ecb1a8ba697b80645a7a926a9d"
@@ -1925,6 +1972,11 @@ is-core-module@^2.0.0:
   dependencies:
     has "^1.0.3"
 
+is-decimal@^1.0.0:
+  version "1.0.4"
+  resolved "https://registry.yarnpkg.com/is-decimal/-/is-decimal-1.0.4.tgz#65a3a5958a1c5b63a706e1b333d7cd9f630d3fa5"
+  integrity sha512-RGdriMmQQvZ2aqaQq3awNA6dCGtKpiDFcOzrTWrDAT2MiWrKQVPmxLGHl7Y2nNu6led0kEyoX0enY0qXYsv9zw==
+
 is-error@^2.2.2:
   version "2.2.2"
   resolved "https://registry.yarnpkg.com/is-error/-/is-error-2.2.2.tgz#c10ade187b3c93510c5470a5567833ee25649843"
@@ -1952,6 +2004,11 @@ is-glob@^4.0.0, is-glob@^4.0.1, is-glob@~4.0.1:
   dependencies:
     is-extglob "^2.1.1"
 
+is-hexadecimal@^1.0.0:
+  version "1.0.4"
+  resolved "https://registry.yarnpkg.com/is-hexadecimal/-/is-hexadecimal-1.0.4.tgz#cc35c97588da4bd49a8eedd6bc4082d44dcb23a7"
+  integrity sha512-gyPJuv83bHMpocVYoqof5VDiZveEoGoFL8m3BXNb2VW8Xs+rz9kqO8LOQ5DH6EsuvilT1ApazU0pyl+ytbPtlw==
+
 is-installed-globally@^0.3.1:
   version "0.3.1"
   resolved "https://registry.yarnpkg.com/is-installed-globally/-/is-installed-globally-0.3.1.tgz#679afef819347a72584617fd19497f010b8ed35f"
@@ -2320,6 +2377,21 @@ md5-o-matic@^0.1.1:
   resolved "https://registry.yarnpkg.com/md5-o-matic/-/md5-o-matic-0.1.1.tgz#822bccd65e117c514fab176b25945d54100a03c3"
   integrity sha1-givM1l4RfFFPqxdrJZRdVBAKA8M=
 
+mdast-util-from-markdown@^0.8.1:
+  version "0.8.1"
+  resolved "https://registry.yarnpkg.com/mdast-util-from-markdown/-/mdast-util-from-markdown-0.8.1.tgz#781371d493cac11212947226190270c15dc97116"
+  integrity sha512-qJXNcFcuCSPqUF0Tb0uYcFDIq67qwB3sxo9RPdf9vG8T90ViKnksFqdB/Coq2a7sTnxL/Ify2y7aIQXDkQFH0w==
+  dependencies:
+    "@types/mdast" "^3.0.0"
+    mdast-util-to-string "^1.0.0"
+    micromark "~2.10.0"
+    parse-entities "^2.0.0"
+
+mdast-util-to-string@^1.0.0:
+  version "1.1.0"
+  resolved "https://registry.yarnpkg.com/mdast-util-to-string/-/mdast-util-to-string-1.1.0.tgz#27055500103f51637bd07d01da01eb1967a43527"
+  integrity sha512-jVU0Nr2B9X3MU4tSK7JP1CMkSvOj7X5l/GboG1tKRw52lLF1x2Ju92Ms9tNetCcbfX3hzlM73zYo2NKkWSfF/A==
+
 mem@^6.1.0:
   version "6.1.0"
   resolved "https://registry.yarnpkg.com/mem/-/mem-6.1.0.tgz#846eca0bd4708a8f04b9c3f3cd769e194ae63c5c"
@@ -2338,6 +2410,14 @@ merge2@^1.2.3, merge2@^1.3.0:
   resolved "https://registry.yarnpkg.com/merge2/-/merge2-1.3.0.tgz#5b366ee83b2f1582c48f87e47cf1a9352103ca81"
   integrity sha512-2j4DAdlBOkiSZIsaXk4mTE3sRS02yBHAtfy127xRV3bQUFqXkjHCHLW6Scv7DwNRbIWNHH8zpnz9zMaKXIdvYw==
 
+micromark@~2.10.0:
+  version "2.10.1"
+  resolved "https://registry.yarnpkg.com/micromark/-/micromark-2.10.1.tgz#cd73f54e0656f10e633073db26b663a221a442a7"
+  integrity sha512-fUuVF8sC1X7wsCS29SYQ2ZfIZYbTymp0EYr6sab3idFjigFFjGa5UwoniPlV9tAgntjuapW1t9U+S0yDYeGKHQ==
+  dependencies:
+    debug "^4.0.0"
+    parse-entities "^2.0.0"
+
 micromatch@^4.0.2:
   version "4.0.2"
   resolved "https://registry.yarnpkg.com/micromatch/-/micromatch-4.0.2.tgz#4fcb0999bf9fbc2fcbdd212f6d629b9a56c39259"
@@ -2474,7 +2554,7 @@ move-concurrently@^1.0.1:
     rimraf "^2.5.4"
     run-queue "^1.0.3"
 
-ms@^2.0.0, ms@^2.1.1, ms@^2.1.2:
+ms@2.1.2, ms@^2.0.0, ms@^2.1.1, ms@^2.1.2:
   version "2.1.2"
   resolved "https://registry.yarnpkg.com/ms/-/ms-2.1.2.tgz#d09d1f357b443f493382a8eb3ccd183872ae6009"
   integrity sha512-sGkPx+VjMtmA6MX27oA4FBFELFCZZ4S4XqeGOXCv68tT+jb3vk/RyaKWP0PTKyWtmLSM0b+adUTEvbs1PEaH2w==
@@ -2734,6 +2814,18 @@ parent-module@^1.0.0:
   dependencies:
     callsites "^3.0.0"
 
+parse-entities@^2.0.0:
+  version "2.0.0"
+  resolved "https://registry.yarnpkg.com/parse-entities/-/parse-entities-2.0.0.tgz#53c6eb5b9314a1f4ec99fa0fdf7ce01ecda0cbe8"
+  integrity sha512-kkywGpCcRYhqQIchaWqZ875wzpS/bMKhz5HnN3p7wveJTkTtyAB/AlnS0f8DFSqYW1T82t6yEAkEcB+A1I3MbQ==
+  dependencies:
+    character-entities "^1.0.0"
+    character-entities-legacy "^1.0.0"
+    character-reference-invalid "^1.0.0"
+    is-alphanumerical "^1.0.0"
+    is-decimal "^1.0.0"
+    is-hexadecimal "^1.0.0"
+
 parse-json@5.1.0, parse-json@^5.0.0:
   version "5.1.0"
   resolved "https://registry.yarnpkg.com/parse-json/-/parse-json-5.1.0.tgz#f96088cdf24a8faa9aea9a009f2d9d942c999646"