fix cycle detection

2 files changed, 53 insertions, 8 deletions

diff --git a/lib/ohai/runner.rb b/lib/ohai/runner.rb
index 287cb0da..73e0ddce 100644
--- a/lib/ohai/runner.rb
+++ b/lib/ohai/runner.rb
@@ -41,12 +41,11 @@ module Ohai
       visited = [plugin]
       while !visited.empty?
         p = visited.pop
-        unless force
-          next if p.has_run?
-        end
+
+        next if p.has_run? unless force
 
         if visited.include?(p)
-          raise DependencyCycleError, "Dependency cycle detected. Please examine the following plugin files: #{cycle_sources(visited, p).join(", ")}"
+          raise DependencyCycleError, "Dependency cycle detected. Please refer to the following plugin files: #{cycle_sources(visited, p).join(", ") }"
         end
 
         dependency_providers = fetch_providers(p.dependencies)
@@ -55,8 +54,7 @@ module Ohai
         if dependency_providers.empty?
           @safe_run ? p.safe_run : p.run
         else
-          visited << p << dependency_providers
-          visited.flatten!
+          visited << p << dependency_providers.first
         end
       end
     end
diff --git a/spec/unit/runner_spec.rb b/spec/unit/runner_spec.rb
index c9dfe805..4cb73e62 100644
--- a/spec/unit/runner_spec.rb
+++ b/spec/unit/runner_spec.rb
@@ -120,7 +120,7 @@ describe Ohai::Runner, "run_plugin" do
         @ohai.attributes[:other] = Mash.new
         @ohai.attributes[:other][:providers] = [@plugin3]
 
-        @runner.should_receive(:fetch_providers).twice.with(["thing"]).and_return([@plugin1, @plugin2])
+        @runner.should_receive(:fetch_providers).exactly(3).times.with(["thing"]).and_return([@plugin1, @plugin2])
         @runner.should_receive(:fetch_providers).twice.with([]).and_return([])
         @runner.run_plugin(@plugin3)
       end
@@ -161,7 +161,7 @@ describe Ohai::Runner, "run_plugin" do
       @ohai.attributes[:three][:providers] = [@plugin3]
 
       @runner.should_receive(:fetch_providers).twice.with([]).and_return([])
-      @runner.should_receive(:fetch_providers).twice.with(["one", "two"]).and_return([@plugin1, @plugin2])
+      @runner.should_receive(:fetch_providers).exactly(3).times.with(["one", "two"]).and_return([@plugin1, @plugin2])
       @runner.run_plugin(@plugin3)
     end
 
@@ -196,6 +196,53 @@ describe Ohai::Runner, "run_plugin" do
       expect { @runner.run_plugin(@plugin1) }.to raise_error(Ohai::DependencyCycleError)
     end
   end
+
+  describe "when A depends on B and C, and B depends on C" do
+    before(:each) do
+      @ohai = Ohai::System.new
+      @runner = Ohai::Runner.new(@ohai, true)
+
+      klassA = Ohai.plugin { provides("A"); depends("B", "C"); collect_data { } }
+      klassB = Ohai.plugin { provides("B"); depends("C"); collect_data { } }
+      klassC = Ohai.plugin { provides("C"); collect_data { } }
+
+      @plugins = []
+      [klassA, klassB, klassC].each do |klass|
+        @plugins << klass.new(@ohai, "")
+      end
+      @pluginA, @pluginB, @pluginC = @plugins
+
+      @ohai.attributes[:A] = Mash.new
+      @ohai.attributes[:A][:providers] = [@pluginA]
+      @ohai.attributes[:B] = Mash.new
+      @ohai.attributes[:B][:providers] = [@pluginB]
+      @ohai.attributes[:C] = Mash.new
+      @ohai.attributes[:C][:providers] = [@pluginC]
+      
+      @runner.stub(:fetch_providers).with(["C"]).and_return([@pluginC])
+      @runner.stub(:fetch_providers).with([]).and_return([])
+    end
+
+    it "should not detect a cycle when B is the first provider returned" do
+      @runner.stub(:fetch_providers).with(["B", "C"]).and_return([@pluginB, @pluginC])
+      Ohai::Log.should_not_receive(:error).with(/DependencyCycleError/)
+      @runner.run_plugin(@pluginA)
+
+      @plugins.each do |plugin|
+        plugin.has_run?.should be_true
+      end
+    end
+
+    it "should not detect a cycle when C is the first provider returned" do
+      @runner.stub(:fetch_providers).with(["B", "C"]).and_return([@pluginC, @pluginB])
+      Ohai::Log.should_not_receive(:error).with(/DependencyCycleError/)
+      @runner.run_plugin(@pluginA)
+
+      @plugins.each do |plugin|
+        plugin.has_run?.should be_true
+      end
+    end
+  end
 end
 
 describe Ohai::Runner, "fetch_providers" do