Migrated tests to jest

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

test/fibonacci/fibonacci.js

@@ -1,6 +0,0 @@
-const fibonacci = n =>
-Array.from({ length: n }).reduce(
-(acc, val, i) => acc.concat(i > 1 ? acc[i - 1] + acc[i - 2] : i),
-[]
-);
-module.exports = fibonacci;