Add methods to query for template/file existence in run context

- Convenience methods added to CookbookVersion to query if a cookbook
  file or template is available for a given node in that cookbook
- Convenience methods added to RunContext to query the existence of
  cookbook files or templates

6 files changed, 119 insertions, 26 deletions

diff --git a/lib/chef/cookbook_version.rb b/lib/chef/cookbook_version.rb
index 4e8b2a048e..5bd0ca064c 100644
--- a/lib/chef/cookbook_version.rb
+++ b/lib/chef/cookbook_version.rb
@@ -265,6 +265,18 @@ class Chef
       end
     end
 
+    # Query whether a template file +template_filename+ is available. File
+    # specificity for the given +node+ is obeyed in the lookup.
+    def has_template_for_node?(node, template_filename)
+      !!find_preferred_manifest_record(node, :templates, template_filename)
+    end
+
+    # Query whether a cookbook_file file +cookbook_filename+ is available. File
+    # specificity for the given +node+ is obeyed in the lookup.
+    def has_cookbook_file_for_node?(node, cookbook_filename)
+      !!find_preferred_manifest_record(node, :files, cookbook_filename)
+    end
+
     # Determine the most specific manifest record for the given
     # segment/filename, given information in the node. Throws
     # FileNotFound if there is no such segment and filename in the
@@ -278,14 +290,7 @@ class Chef
     #   :checksum => "1234"
     # }
     def preferred_manifest_record(node, segment, filename)
-      preferences = preferences_for_path(node, segment, filename)
-
-      # ensure that we generate the manifest, which will also generate
-      # @manifest_records_by_path
-      manifest
-
-      # in order of prefernce, look for the filename in the manifest
-      found_pref = preferences.find {|preferred_filename| @manifest_records_by_path[preferred_filename] }
+      found_pref = find_preferred_manifest_record(node, segment, filename)
       if found_pref
         @manifest_records_by_path[found_pref]
       else
@@ -567,6 +572,17 @@ class Chef
 
     private
 
+    def find_preferred_manifest_record(node, segment, filename)
+      preferences = preferences_for_path(node, segment, filename)
+
+      # ensure that we generate the manifest, which will also generate
+      # @manifest_records_by_path
+      manifest
+
+      # in order of prefernce, look for the filename in the manifest
+      preferences.find {|preferred_filename| @manifest_records_by_path[preferred_filename] }
+    end
+
     # For each filename, produce a mapping of base filename (i.e. recipe name
     # or attribute file) to on disk location
     def filenames_by_name(filenames)
diff --git a/lib/chef/run_context.rb b/lib/chef/run_context.rb
index 6477431967..4d431116f9 100644
--- a/lib/chef/run_context.rb
+++ b/lib/chef/run_context.rb
@@ -204,6 +204,20 @@ class Chef
       @loaded_attributes["#{cookbook}::#{attribute_file}"] = true
     end
 
+    ##
+    # Cookbook File Introspection
+
+    def has_template_in_cookbook?(cookbook, template_name)
+      cookbook = cookbook_collection[cookbook]
+      cookbook.has_template_for_node?(node, template_name)
+    end
+
+    def has_cookbook_file_in_cookbook?(cookbook, cb_file_name)
+      cookbook = cookbook_collection[cookbook]
+      cookbook.has_cookbook_file_for_node?(node, cb_file_name)
+    end
+
+
     private
 
     def loaded_recipe(cookbook, recipe)
diff --git a/spec/support/lib/library_load_order.rb b/spec/support/lib/library_load_order.rb
new file mode 100644
index 0000000000..c47a2f2c74
--- /dev/null
+++ b/spec/support/lib/library_load_order.rb
@@ -0,0 +1,22 @@
+# Helper module to track the load order of library files.
+# Used by `cookbook_compiler_spec.rb`
+#
+# This module must be loaded for any tests that load the cookbook
+# data/run_context/cookbooks/test to succeed.
+module LibraryLoadOrder
+  extend self
+
+  def load_order
+    @load_order ||= []
+  end
+
+  def reset!
+    @load_order = nil
+  end
+
+  def record(file)
+    load_order << file
+  end
+end
+
+
diff --git a/spec/unit/cookbook_version_spec.rb b/spec/unit/cookbook_version_spec.rb
index 85e1db1fae..d186ef01be 100644
--- a/spec/unit/cookbook_version_spec.rb
+++ b/spec/unit/cookbook_version_spec.rb
@@ -130,6 +130,12 @@ describe Chef::CookbookVersion do
       @cookbook_version.provider_filenames   = @cookbook[:provider_filenames]
       @cookbook_version.root_filenames       = @cookbook[:root_filenames]
       @cookbook_version.metadata_filenames   = @cookbook[:metadata_filenames]
+
+      # Used to test file-specificity related file lookups
+      @node = Chef::Node.new
+      @node.set[:platform] = "ubuntu"
+      @node.set[:platform_version] = "13.04"
+      @node.name("testing")
     end
 
     it "generates a manifest containing the cookbook's files" do
@@ -211,6 +217,16 @@ describe Chef::CookbookVersion do
       readme["specificity"].should == "default"
     end
 
+    it "determines whether a template is available for a given node" do
+      @cookbook_version.should have_template_for_node(@node, "configuration.erb")
+      @cookbook_version.should_not have_template_for_node(@node, "missing.erb")
+    end
+
+    it "determines whether a cookbook_file is available for a given node" do
+      @cookbook_version.should have_cookbook_file_for_node(@node, "giant_blob.tgz")
+      @cookbook_version.should_not have_cookbook_file_for_node(@node, "missing.txt")
+    end
+
     describe "raises an error when attempting to load a missing cookbook_file and" do
       before do
         node = Chef::Node.new.tap do |n|
diff --git a/spec/unit/run_context/cookbook_compiler_spec.rb b/spec/unit/run_context/cookbook_compiler_spec.rb
index 0c5e568a13..fe6bef5618 100644
--- a/spec/unit/run_context/cookbook_compiler_spec.rb
+++ b/spec/unit/run_context/cookbook_compiler_spec.rb
@@ -17,23 +17,7 @@
 #
 
 require 'spec_helper'
-
-# Keeps track of what file got loaded in what order.
-module LibraryLoadOrder
-  extend self
-
-  def load_order
-    @load_order ||= []
-  end
-
-  def reset!
-    @load_order = nil
-  end
-
-  def record(file)
-    load_order << file
-  end
-end
+require 'support/lib/library_load_order'
 
 # These tests rely on fixture data in spec/data/run_context/cookbooks.
 #
diff --git a/spec/unit/run_context_spec.rb b/spec/unit/run_context_spec.rb
index 51fa0e81f9..d75d6628bb 100644
--- a/spec/unit/run_context_spec.rb
+++ b/spec/unit/run_context_spec.rb
@@ -19,6 +19,7 @@
 #
 
 require 'spec_helper'
+require 'support/lib/library_load_order'
 
 Chef::Log.level = :debug
 
@@ -42,7 +43,7 @@ describe Chef::RunContext do
     @run_context.node.should == @node
   end
 
-  describe "after loading the cookbooks" do
+  describe "loading cookbooks for a run list" do
     before do
       @run_context.load(@node.run_list.expand('_default'))
     end
@@ -73,6 +74,46 @@ describe Chef::RunContext do
       @node.should_not_receive(:from_file)
       @node.include_attribute("test::george")
     end
+
+
+  end
+
+  describe "querying the contents of cookbooks" do
+    before do
+      @chef_repo_path = File.expand_path(File.join(CHEF_SPEC_DATA, "cookbooks"))
+      cl = Chef::CookbookLoader.new(@chef_repo_path)
+      cl.load_cookbooks
+      @cookbook_collection = Chef::CookbookCollection.new(cl)
+      @node = Chef::Node.new
+      @node.set[:platform] = "ubuntu"
+      @node.set[:platform_version] = "13.04"
+      @node.name("testing")
+      @events = Chef::EventDispatch::Dispatcher.new
+      @run_context = Chef::RunContext.new(@node, @cookbook_collection, @events)
+    end
+
+
+    it "queries whether a given cookbook has a specific template" do
+      @run_context.should have_template_in_cookbook("openldap", "test.erb")
+      @run_context.should_not have_template_in_cookbook("openldap", "missing.erb")
+    end
+
+    it "errors when querying for a template in a not-available cookbook" do
+      expect do
+        @run_context.has_template_in_cookbook?("no-such-cookbook", "foo.erb")
+      end.to raise_error(Chef::Exceptions::CookbookNotFound)
+    end
+
+    it "queries whether a given cookbook has a specific cookbook_file" do
+      @run_context.should have_cookbook_file_in_cookbook("java", "java.response")
+      @run_context.should_not have_cookbook_file_in_cookbook("java", "missing.txt")
+    end
+
+    it "errors when querying for a cookbook_file in a not-available cookbook" do
+      expect do
+        @run_context.has_cookbook_file_in_cookbook?("no-such-cookbook", "foo.txt")
+      end.to raise_error(Chef::Exceptions::CookbookNotFound)
+    end
   end
 
 end