Migrated tests to jest

Used jest-codemods to migrate, will have to pass everything by hand before we can merge.

test6/sampleSize/sampleSize.js

@@ -0,0 +1,9 @@
+const sampleSize = ([...arr], n = 1) => {
+let m = arr.length;
+while (m) {
+const i = Math.floor(Math.random() * m--);
+[arr[m], arr[i]] = [arr[i], arr[m]];
+}
+return arr.slice(0, n);
+};
+module.exports = sampleSize;