Add support for rendering jinja template as yaml

This also adds support for using custom loaders in job definitions

not just job-templates and builders. I have also added unit tests for include-jinja2-as-yaml custom loader.

Example usage:

        - axis:
            type: user-defined
            name: VERSIONS
            values:
                !include-jinja2-as-yaml: versions.j2.yaml.inc

Where versions.j2.yaml.inc is

{% for possible_versions in configuration["possible_versions"] %}
- {{ possible_versions["versions"] }}
{% endfor -%}

Change-Id: I15a431d5a86b29d704efda8576965ade2b7dcd2f

3 files changed, 41 insertions, 0 deletions

diff --git a/tests/yamlparser/fixtures/jinja-as-yaml-include01.xml b/tests/yamlparser/fixtures/jinja-as-yaml-include01.xml
new file mode 100644
index 00000000..732bb2c4
--- /dev/null
+++ b/tests/yamlparser/fixtures/jinja-as-yaml-include01.xml
@@ -0,0 +1,31 @@
+<?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>
+    <hudson.model.ParametersDefinitionProperty>
+      <parameterDefinitions>
+        <hudson.model.ChoiceParameterDefinition>
+          <name>TEST_CHOICE</name>
+          <description/>
+          <choices class="java.util.Arrays$ArrayList">
+            <a class="string-array">
+              <string>a</string>
+              <string>b</string>
+              <string>c</string>
+            </a>
+          </choices>
+        </hudson.model.ChoiceParameterDefinition>
+      </parameterDefinitions>
+    </hudson.model.ParametersDefinitionProperty>
+  </properties>
+  <scm class="hudson.scm.NullSCM"/>
+  <builders/>
+  <publishers/>
+  <buildWrappers/>
+</project>
diff --git a/tests/yamlparser/fixtures/jinja-as-yaml-include01.yaml b/tests/yamlparser/fixtures/jinja-as-yaml-include01.yaml
new file mode 100644
index 00000000..2ea430f0
--- /dev/null
+++ b/tests/yamlparser/fixtures/jinja-as-yaml-include01.yaml
@@ -0,0 +1,7 @@
+- job:
+    name: test-job-as-yaml
+    parameters:
+        - choice:
+            name: TEST_CHOICE
+            choices:
+                !include-jinja2-as-yaml: jinja-as-yaml-include01.yaml.inc
diff --git a/tests/yamlparser/fixtures/jinja-as-yaml-include01.yaml.inc b/tests/yamlparser/fixtures/jinja-as-yaml-include01.yaml.inc
new file mode 100644
index 00000000..c1c3c8b3
--- /dev/null
+++ b/tests/yamlparser/fixtures/jinja-as-yaml-include01.yaml.inc
@@ -0,0 +1,3 @@
+{% for item in ['a', 'b', 'c'] %}
+- {{ item }}
+{% endfor -%}