Generates a git repository with dual history and some branches on top (for fixing a Jenkins performance bug)

generate-test-git.sh

#!/bin/bash

# Creates a git repository called "testgit-generated"
# with two separate histories branching from the initial
# commit, each being 500 commits long.
# On top of each, we create 200 branches with one extra
# commit per branch.
# Should take around 30 seconds.

set -e

# Create repo
mkdir testgit-generated
cd testgit-generated
echo start > myfile
git init
git add myfile
git commit -m "Initial commit"
git branch init

# Create history 1 (500 commits)
git checkout -b history1 init
for i in {1..500}; do
  echo "commit $i"
  date +%s%N >> myfile
  git commit -am "`date +%s%N`"
done

# Create 200 branches on top of history 1
for i in {1..200}; do
  echo "branch $i"
  git reset --hard
  git checkout -f -b `date +%s%N` history1
  date +%s%N >> myfile
  git commit -am "`date +%s%N`"
done

# Create history 2 (500 commits)
git checkout -b history2 init
for i in {1..500}; do
  echo "commit $i"
  date +%s%N >> myfile
  git commit -am "`date +%s%N`"
done

# Create 200 branches on top of history 2
for i in {1..200}; do
  echo "branch $i"
  git reset --hard
  git checkout -f -b `date +%s%N` history2
  date +%s%N >> myfile
  git commit -am "`date +%s%N`"
done