Fix #1907 (or sort) - 'require' puppet function

This function acts exactly as the 'include' function, but also
adds an ordering relation between the included class and the class
where the require function is.

Signed-off-by: Brice Figureau <brice-puppet@daysofwonder.com>

3 files changed, 97 insertions, 0 deletions

diff --git a/lib/puppet/parser/functions/require.rb b/lib/puppet/parser/functions/require.rb
new file mode 100644
index 000000000..7d73831b8
--- /dev/null
+++ b/lib/puppet/parser/functions/require.rb
@@ -0,0 +1,34 @@
+# Requires the specified classes
+Puppet::Parser::Functions::newfunction(:require,
+        :doc =>"Evaluate one or more classes,  adding the required class as a dependency.
+
+The relationship metaparameters work well for specifying relationships
+between individual resources, but they can be clumsy for specifying 
+relationships between classes.  This function is a superset of the
+'include' function, adding a class relationship so that the requiring
+class depends on the required class.
+
+.. Warning::
+  using require in place of include can lead to unwanted dependency cycles.
+  For instance the following manifest, with 'require' instead of 'include'
+  would produce a nasty dependence cycle, because notify imposes a before
+  between File[/foo] and Service[foo]::
+
+    class myservice {
+       service { foo: ensure => running }
+    }
+
+    class otherstuff {
+       include myservice
+       file { '/foo': notify => Service[foo] }
+    }
+
+") do |vals|
+        send(:function_include, vals)
+        vals = [vals] unless vals.is_a?(Array)
+
+        # add a relation from ourselves to each required klass
+        vals.each do |klass|
+            compiler.catalog.add_edge(resource, findresource(:class, klass))
+        end
+end
diff --git a/spec/integration/parser/functions/require.rb b/spec/integration/parser/functions/require.rb
new file mode 100755
index 000000000..68a1e0b54
--- /dev/null
+++ b/spec/integration/parser/functions/require.rb
@@ -0,0 +1,27 @@
+#!/usr/bin/env ruby
+
+require File.dirname(__FILE__) + '/../../../spec_helper'
+
+describe "the require function" do
+
+    before :each do
+        @parser = Puppet::Parser::Parser.new :Code => ""
+        @node = Puppet::Node.new("mynode")
+        @compiler = Puppet::Parser::Compiler.new(@node, @parser)
+
+        @compiler.send(:evaluate_main)
+        @scope = @compiler.topscope
+        # preload our functions
+        Puppet::Parser::Functions.function(:include)
+        Puppet::Parser::Functions.function(:require)
+    end
+
+    it "should add a relationship between the 'required' class and our class" do
+        @parser.newclass("requiredclass")
+
+        @scope.function_require("requiredclass")
+
+        @compiler.catalog.edge?(@scope.resource,@compiler.findresource(:class,"requiredclass")).should be_true
+    end
+
+end
diff --git a/spec/unit/parser/functions/require.rb b/spec/unit/parser/functions/require.rb
new file mode 100755
index 000000000..67a5baeb9
--- /dev/null
+++ b/spec/unit/parser/functions/require.rb
@@ -0,0 +1,36 @@
+#!/usr/bin/env ruby
+
+require File.dirname(__FILE__) + '/../../../spec_helper'
+
+describe "the require function" do
+
+    before :each do
+        @catalog = stub 'catalog'
+        @compiler = stub 'compiler', :catalog => @catalog
+        @scope = Puppet::Parser::Scope.new()
+        @scope.stubs(:resource).returns("ourselves")
+        @scope.stubs(:findresource)
+        @scope.stubs(:compiler).returns(@compiler)
+    end
+
+    it "should exist" do
+        Puppet::Parser::Functions.function("require").should == "function_require"
+    end
+
+    it "should delegate to the 'include' puppet function" do
+        @catalog.stubs(:add_edge)
+        @scope.expects(:function_include).with("myclass")
+
+        @scope.function_require("myclass")
+    end
+
+    it "should add a catalog edge from our parent resource to the included one" do
+        @scope.stubs(:function_include).with("myclass")
+        @scope.stubs(:findresource).with(:class, "myclass").returns("includedclass")
+
+        @catalog.expects(:add_edge).with("ourselves","includedclass")
+
+        @scope.function_require("myclass")
+    end
+
+end