diff --git a/lib/util/index.ts b/lib/util/index.ts
index 017f4fa8fa7445..58b1c8631c6788 100644
--- a/lib/util/index.ts
+++ b/lib/util/index.ts
@@ -23,3 +23,21 @@ export async function resolveFile(file: string): Promise<string> {
   }
   return join(pkg, '../', file);
 }
+
+export function sampleSize(array: string[], n: number): string[] {
+  const length = array == null ? 0 : array.length;
+  if (!length || n < 1) {
+    return [];
+  }
+  // eslint-disable-next-line no-param-reassign
+  n = n > length ? length : n;
+  let index = 0;
+  const lastIndex = length - 1;
+  const result = [...array];
+  while (index < n) {
+    const rand = index + Math.floor(Math.random() * (lastIndex - index + 1));
+    [result[rand], result[index]] = [result[index], result[rand]];
+    index += 1;
+  }
+  return result.slice(0, n);
+}
diff --git a/lib/util/string.ts b/lib/util/string.ts
index 2cad78d692bc9c..a52501fb99c7de 100644
--- a/lib/util/string.ts
+++ b/lib/util/string.ts
@@ -23,3 +23,11 @@ export function replaceAt(
     content.substr(index + oldString.length)
   );
 }
+
+export function camelCase(input: string): string {
+  return input
+    .replace(/(?:^\w|[A-Z]|\b\w)/g, (char, index) => {
+      return index === 0 ? char.toLowerCase() : char.toUpperCase();
+    })
+    .replace(/-/g, '');
+}
diff --git a/lib/versioning/ruby/version.ts b/lib/versioning/ruby/version.ts
index 4a5a1445260aca..7999090829b17b 100644
--- a/lib/versioning/ruby/version.ts
+++ b/lib/versioning/ruby/version.ts
@@ -24,9 +24,9 @@ const floor = (version: string): string =>
 // istanbul ignore next
 const incrementLastSegment = (version: string): string => {
   const segments = create(version).release().getSegments();
-  const nextLast = parseInt(segments[segments.length - 1], 10) + 1;
+  const nextLast = parseInt(segments.pop(), 10) + 1;
 
-  return [...segments.slice(0, -1), nextLast].join('.');
+  return [...segments, nextLast].join('.');
 };
 
 // istanbul ignore next
diff --git a/lib/workers/pr/index.ts b/lib/workers/pr/index.ts
index 98f19864bc9a0c..31e9ebd8c7f390 100644
--- a/lib/workers/pr/index.ts
+++ b/lib/workers/pr/index.ts
@@ -8,6 +8,7 @@ import {
 import { logger } from '../../logger';
 import { PlatformPrOptions, Pr, platform } from '../../platform';
 import { BranchStatus } from '../../types';
+import { sampleSize } from '../../util';
 import { BranchConfig, PrResult } from '../common';
 import { getPrBody } from './body';
 import { ChangeLogError } from './changelog';
@@ -522,19 +523,3 @@ export async function checkAutoMerge(
   logger.debug('No automerge');
   return false;
 }
-
-function sampleSize(array: string[], n: number) {
-  const length = array == null ? 0 : array.length;
-  if (!length || n < 1) {
-    return [];
-  }
-  n = n > length ? length : n;
-  let index = -1;
-  const lastIndex = length - 1;
-  const result = [...array];
-  while (++index < n) {
-    const rand = index + Math.floor(Math.random() * (lastIndex - index + 1));
-    [result[rand], result[index]] = [result[index], result[rand]];
-  }
-  return result.slice(0, n);
-}
diff --git a/test/globals.ts b/test/globals.ts
index d8c3db8ff91a22..bb1baa4077aa02 100644
--- a/test/globals.ts
+++ b/test/globals.ts
@@ -11,3 +11,7 @@ jest.mock('../lib/logger');
 beforeAll(() => {
   nock.disableNetConnect();
 });
+
+afterAll(() => {
+  global?.gc();
+});
diff --git a/tools/generate-imports.ts b/tools/generate-imports.ts
index 60f612cdb70b6d..36598390dd06cb 100644
--- a/tools/generate-imports.ts
+++ b/tools/generate-imports.ts
@@ -1,6 +1,8 @@
 import fs from 'fs-extra';
 import shell from 'shelljs';
 
+import { camelCase } from '../lib/util/string';
+
 shell.echo('generating imports');
 const newFiles = new Set();
 
@@ -25,14 +27,6 @@ async function updateFile(file: string, code: string): Promise<void> {
   newFiles.add(file);
 }
 
-function camelCase(input: string) {
-  return input
-    .replace(/(?:^\w|[A-Z]|\b\w)/g, function (char, index) {
-      return index === 0 ? char.toLowerCase() : char.toUpperCase();
-    })
-    .replace(/-/g, '');
-}
-
 async function generate({
   path,
   types,