Allow bundle viz to work with dependencies satisfied by prereleases.

Suppose a Gemfile specifies a dependency, `foo`:

  foo

Let's say `foo` requires a certain `bar`:

  foo
    bar (>= 0.5)

If this dependency happens to be satisfied by a prerelease `bar`, e.g.,
0.6.pre, then `bundle viz` will error.

The cause of this error is that `Bundler::Graph#_populate_relations`
executes

  child_dependencies = dependency.to_spec.runtime_dependencies.to_set

and if `dependency` (here, `bar`), is a prerelease, then
`dependency.to_spec` will be `nil` on Rubygems 2.4.0 and higher because
of changes to `#to_spec`.

By forcing `dependency.prerelease = true`, then `to_spec` won't ignore
the prerelease `bar` dependency, which prevents `dependency.to_spec` to
from being `nil`.

This should address GitHub issues 3621 and 3217.

1 files changed, 3 insertions, 1 deletions

diff --git a/Rakefile b/Rakefile
index fd3bfdd983..ba09894103 100644
--- a/Rakefile
+++ b/Rakefile
@@ -114,8 +114,10 @@ namespace :spec do
       system "sudo sed -i 's/1000::/1000:Travis:/g' /etc/passwd"
       # Strip secure_path so that RVM paths transmit through sudo -E
       system "sudo sed -i '/secure_path/d' /etc/sudoers"
-      # Install groff for the ronn gem
+      # Install groff so ronn can generate man/help pages
       sh "sudo apt-get install groff -y"
+      # Install graphviz so that the viz specs can run
+      sh "sudo apt-get install graphviz -y 2>&1 | tail -n 2"
       if RUBY_VERSION < '1.9'
         # Downgrade Rubygems on 1.8 so Ronn can be required
         # https://github.com/rubygems/rubygems/issues/784