Order component retrieval to favour user defined

Prefer user defined macros over inbuilt entry points, as JJB may
accidentally use a name that has already been used by an end-user to
define a custom macro.

Warn users when they have a macro defined that masks an in-built
component to avoid accidentally changing XML generated with new
releases.

Change-Id: I6cae62d7cc40be6c4a5636a74f151fcce4cdd856

jenkins_jobs/registry.py

@@ -223,20 +223,24 @@ class ModuleRegistry(object):
             logger.debug("Cached entry point group %s = %s",
                          component_list_type, eps)
 
-        if name in eps:
+        # check for macro first
-            func = eps[name].load()
-            func(parser, xml_parent, component_data)
-        else:
-            # Otherwise, see if it's defined as a macro
         component = parser.data.get(component_type, {}).get(name)
         if component:
+            if name in eps:
+                logger.warn("You have a macro ('%s') defined for '%s' "
+                            "component type that is masking an inbuilt "
+                            "definition" % (name, component_type))
+
             for b in component[component_list_type]:
                 # Pass component_data in as template data to this function
                 # so that if the macro is invoked with arguments,
                 # the arguments are interpolated into the real defn.
                 self.dispatch(component_type,
                               parser, xml_parent, b, component_data)
+        elif name in eps:
+            func = eps[name].load()
+            func(parser, xml_parent, component_data)
         else:
-                raise JenkinsJobsException("Unknown entry point or macro '{0}'"
+            raise JenkinsJobsException("Unknown entry point or macro '{0}' "
-                                           " for component type: '{1}'.".
+                                       "for component type: '{1}'.".
                                        format(name, component_type))

tests/yamlparser/fixtures/mask_internal_component.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?>
+<project>
+  <actions/>
+  <description>&lt;!-- Managed by Jenkins Job Builder --&gt;</description>
+  <keepDependencies>false</keepDependencies>
+  <blockBuildWhenDownstreamBuilding>false</blockBuildWhenDownstreamBuilding>
+  <blockBuildWhenUpstreamBuilding>false</blockBuildWhenUpstreamBuilding>
+  <concurrentBuild>false</concurrentBuild>
+  <canRoam>true</canRoam>
+  <properties/>
+  <scm class="hudson.scm.NullSCM"/>
+  <builders>
+    <hudson.tasks.Shell>
+      <command>bash /opt/bin/run_python.sh</command>
+    </hudson.tasks.Shell>
+  </builders>
+  <publishers/>
+  <buildWrappers/>
+</project>

tests/yamlparser/fixtures/mask_internal_component.yaml

@@ -0,0 +1,11 @@
+- builder:
+    name: python
+    builders:
+      - shell:
+          bash {file}
+
+- job:
+    name: mask-internal-module
+    builders:
+      - python:
+          file: '/opt/bin/run_python.sh'