Add command to diagnose common issues

This new command, doctor, checks for common problems.
Currently, it looks for broken dynamic library links in C
extensions.

It scans all of the specifications in the bundle for .bundle files in C
extensions. If any of the dynamic libraries linked against no longer
exist, bundler will report a message to the console.

3 files changed, 164 insertions, 0 deletions

diff --git a/lib/bundler/cli.rb b/lib/bundler/cli.rb
index 621deb0950..5e568995d0 100644
--- a/lib/bundler/cli.rb
+++ b/lib/bundler/cli.rb
@@ -474,6 +474,24 @@ module Bundler
       Inject.new(options, name, version, gems).run
     end
 
+    desc "doctor [OPTIONS]", "Checks the bundle for common problems"
+    long_desc <<-D
+      Doctor scans the OS dependencies of each of the gems requested in the Gemfile. If
+      missing dependencies are detected, Bundler prints them and exits status 1.
+      Otherwise, Bundler prints a success message and exits with a status of 0.
+
+      The bundle's gem dependencies must all be installed to run this command; if
+      they are not, Bundler prints an error message and exits with a status of 2.
+    D
+    method_option "gemfile", :type => :string, :banner =>
+      "Use the specified gemfile instead of Gemfile"
+    method_option "quiet", :type => :boolean, :banner =>
+        "Only output warnings and errors."
+    def doctor
+      require "bundler/cli/doctor"
+      Doctor.new(options).run
+    end
+
     if Bundler.settings[:plugins]
       require "bundler/cli/plugin"
       desc "plugin SUBCOMMAND ...ARGS", "manage the bundler plugins"
diff --git a/lib/bundler/cli/doctor.rb b/lib/bundler/cli/doctor.rb
new file mode 100644
index 0000000000..370e46ac69
--- /dev/null
+++ b/lib/bundler/cli/doctor.rb
@@ -0,0 +1,85 @@
+# frozen_string_literal: true
+
+require "rbconfig"
+
+module Bundler
+  class CLI::Doctor
+    DARWIN_REGEX = /\s+(.+) \(compatibility /
+    LDD_REGEX = /\t\S+ => (\S+) \(\S+\)/
+
+    attr_reader :options
+
+    def initialize(options)
+      @options = options
+    end
+
+    def dylibs_darwin(path)
+      output = `/usr/bin/otool -L "#{path}"`.chomp
+      dylibs = output.split("\n")[1..-1].map {|l| l.match(DARWIN_REGEX).captures[0] }.uniq
+      # ignore @rpath and friends
+      dylibs.reject {|dylib| dylib.start_with? "@" }
+    end
+
+    def dylibs_ldd(path)
+      output = `/usr/bin/ldd "#{path}"`.chomp
+      output.split("\n").map do |l|
+        match = l.match(LDD_REGEX)
+        next if match.nil?
+        match.captures[0]
+      end.compact
+    end
+
+    def dylibs(path)
+      case RbConfig::CONFIG["host_os"]
+      when /darwin/
+        dylibs_darwin(path)
+      when /(linux|solaris|bsd)/
+        dylibs_ldd(path)
+      else # Windows, etc.
+        Bundler.ui.warn("Dynamic library check not supported on this platform.")
+        []
+      end
+    end
+
+    def bundles_for_gem(spec)
+      Dir.glob("#{spec.full_gem_path}/**/*.bundle")
+    end
+
+    def run
+      Bundler.ui.level = "error" if options[:quiet]
+
+      broken_links = {}
+
+      begin
+        definition = Bundler.definition
+        definition.validate_ruby!
+        not_installed = definition.missing_specs
+        raise GemNotFound if not_installed.any?
+      rescue GemNotFound
+        Bundler.ui.error "This bundle's gems must be installed to run this command."
+        Bundler.ui.warn "Install missing gems with `bundle install`."
+        exit 2
+      end
+
+      definition.specs.each do |spec|
+        bundles_for_gem(spec).each do |bundle|
+          bad_paths = dylibs(bundle).select {|f| !File.exist?(f) }
+          if bad_paths.any?
+            broken_links[spec] ||= []
+            broken_links[spec].concat(bad_paths)
+          end
+        end
+      end
+
+      if broken_links.any?
+        Bundler.ui.error "The following gems are missing OS dependencies"
+        broken_links.each do |spec, paths|
+          paths.uniq.each do |path|
+            Bundler.ui.error " * #{spec.name}: #{path}"
+          end
+        end
+        exit 1
+      end
+    end
+  end
+end
diff --git a/spec/commands/doctor_spec.rb b/spec/commands/doctor_spec.rb
new file mode 100644
index 0000000000..236138a6c8
--- /dev/null
+++ b/spec/commands/doctor_spec.rb
@@ -0,0 +1,61 @@
+# frozen_string_literal: true
+require "spec_helper"
+require "stringio"
+require "bundler/cli"
+require "bundler/cli/doctor"
+
+describe "bundle doctor" do
+  before(:each) do
+    @stdout = StringIO.new
+
+    [:error, :warn].each do |method|
+      allow(Bundler.ui).to receive(method).and_wrap_original do |m, message|
+        m.call message
+        @stdout.puts message
+      end
+    end
+  end
+
+  it "exits with no message if the installed gem has no C extensions" do
+    gemfile <<-G
+      source "file://#{gem_repo1}"
+      gem "rack"
+    G
+
+    bundle :install
+    Bundler::CLI::Doctor.new({}).run
+    expect(@stdout.string).to be_empty
+  end
+
+  it "exits with no message if the installed gem's C extension dylib breakage is fine" do
+    gemfile <<-G
+      source "file://#{gem_repo1}"
+      gem "rack"
+    G
+
+    bundle :install
+    doctor = Bundler::CLI::Doctor.new({})
+    expect(doctor).to receive(:bundles_for_gem).exactly(2).times.and_return ["/path/to/rack/rack.bundle"]
+    expect(doctor).to receive(:dylibs).exactly(2).times.and_return ["/usr/lib/libSystem.dylib"]
+    allow(File).to receive(:exist?).and_call_original
+    allow(File).to receive(:exist?).with("/usr/lib/libSystem.dylib").and_return(true)
+    doctor.run
+    expect(@stdout.string).to be_empty
+  end
+
+  it "exits with a message if one of the linked libraries is missing" do
+    gemfile <<-G
+      source "file://#{gem_repo1}"
+      gem "rack"
+    G
+
+    bundle :install
+    doctor = Bundler::CLI::Doctor.new({})
+    expect(doctor).to receive(:bundles_for_gem).exactly(2).times.and_return ["/path/to/rack/rack.bundle"]
+    expect(doctor).to receive(:dylibs).exactly(2).times.and_return ["/usr/local/opt/icu4c/lib/libicui18n.57.1.dylib"]
+    allow(File).to receive(:exist?).and_call_original
+    allow(File).to receive(:exist?).with("/usr/local/opt/icu4c/lib/libicui18n.57.1.dylib").and_return(false)
+    expect { doctor.run }.to raise_error SystemExit
+    expect(@stdout.string).to include("libicui18n.57.1.dylib")
+  end
+end