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, 0 deletions

diff --git a/lib/bundler/graph.rb b/lib/bundler/graph.rb
index 0b5c5723b4..fbb5bd0248 100644
--- a/lib/bundler/graph.rb
+++ b/lib/bundler/graph.rb
@@ -36,6 +36,9 @@ module Bundler
         else
           tmp = Set.new
           parent_dependencies.each do |dependency|
+            # if the dependency is a prerelease, allow to_spec to be non-nil
+            dependency.prerelease = true
+
             child_dependencies = dependency.to_spec.runtime_dependencies.to_set
             @relations[dependency.name] += child_dependencies.map(&:name).to_set
             tmp += child_dependencies