Merge ~cjwatson/launchpad:cibuild-traversal into launchpad:master

[Colin Watson]

Add +cibuild stepthrough navigation on BuilderSet

This is useful when repairing the build farm after outages, or otherwise needing to look up a CI build by its ID alone. It goes with similar stepthroughs for other build types.

[Jürgen Gmach (jugmac00)]

Code changes look good. I have a question about the used decorator though.

review: Approve

diff --git a/lib/lp/buildmaster/browser/builder.py b/lib/lp/buildmaster/browser/builder.py
index 6fa3e16..88b3d20 100644
--- a/lib/lp/buildmaster/browser/builder.py
+++ b/lib/lp/buildmaster/browser/builder.py
@@ -42,6 +42,7 @@ from lp.buildmaster.interfaces.builder import (
     IBuilder,
     IBuilderSet,
     )
+from lp.code.interfaces.cibuild import ICIBuildSet
 from lp.code.interfaces.sourcepackagerecipebuild import (
     ISourcePackageRecipeBuildSource,
     )
@@ -108,6 +109,13 @@ class BuilderSetNavigation(GetitemNavigation):
             return None
         return self.redirectSubTree(canonical_url(build, request=self.request))
 
+    @stepthrough('+cibuild')
+    def traverse_cibuild(self, name):
+        build = get_build_by_id_str(ICIBuildSet, name)
+        if build is None:
+            return None
+        return self.redirectSubTree(canonical_url(build, request=self.request))
+
 
 class BuilderSetBreadcrumb(Breadcrumb):
     """Builds a breadcrumb for an `IBuilderSet`."""
diff --git a/lib/lp/buildmaster/browser/tests/test_builder.py b/lib/lp/buildmaster/browser/tests/test_builder.py
index 0a3ce50..4037d31 100644
--- a/lib/lp/buildmaster/browser/tests/test_builder.py
+++ b/lib/lp/buildmaster/browser/tests/test_builder.py
@@ -116,6 +116,18 @@ class TestBuilderSetNavigation(TestCaseWithFactory):
         browser.open(url)
         self.assertEqual(expected_url, browser.url)
 
+    def test_ci_build_api_redirects(self):
+        build = self.factory.makeCIBuild()
+        url = (
+            "http://api.launchpad.test/devel/builders/+cibuild/%s" % build.id)
+        expected_url = (
+            "http://api.launchpad.test/devel" +
+            canonical_url(build, path_only_if_possible=True))
+        logout()
+        browser = setupBrowser()
+        browser.open(url)
+        self.assertEqual(expected_url, browser.url)
+
 
 class TestBuildersHomepage(TestCaseWithFactory, BuildCreationMixin):