Refactor merge mode name lookup

This is repeated in a few places, centralize it.

Change-Id: I7bbed1f5f9faad31affa71ef17fbfc1740c54db8

4 files changed, 14 insertions, 12 deletions

diff --git a/zuul/driver/github/githubreporter.py b/zuul/driver/github/githubreporter.py
index e5c5ebfbd..1f44303bd 100644
--- a/zuul/driver/github/githubreporter.py
+++ b/zuul/driver/github/githubreporter.py
@@ -189,8 +189,7 @@ class GithubReporter(BaseReporter):
         merge_mode = item.current_build_set.getMergeMode()
 
         if merge_mode not in self.merge_modes:
-            mode = [x[0] for x in model.MERGER_MAP.items()
-                    if x[1] == merge_mode][0]
+            mode = model.get_merge_mode_name(merge_mode)
             self.log.warning('Merge mode %s not supported by Github', mode)
             raise MergeFailure('Merge mode %s not supported by Github' % mode)
 
diff --git a/zuul/driver/gitlab/gitlabreporter.py b/zuul/driver/gitlab/gitlabreporter.py
index 819c89c47..b909bc3d7 100644
--- a/zuul/driver/gitlab/gitlabreporter.py
+++ b/zuul/driver/gitlab/gitlabreporter.py
@@ -16,9 +16,8 @@ import time
 import logging
 import voluptuous as v
 
+from zuul import model
 from zuul.reporter import BaseReporter
-from zuul.model import MERGER_MERGE_RESOLVE, MERGER_MERGE, MERGER_MAP, \
-    MERGER_SQUASH_MERGE
 from zuul.lib.logutil import get_annotated_logger
 from zuul.driver.gitlab.gitlabsource import GitlabSource
 from zuul.driver.util import scalar_or_list
@@ -33,9 +32,9 @@ class GitlabReporter(BaseReporter):
 
     # Merge modes supported by gitlab
     merge_modes = {
-        MERGER_MERGE: 'merge',
-        MERGER_MERGE_RESOLVE: 'merge',
-        MERGER_SQUASH_MERGE: 'squash'
+        model.MERGER_MERGE: 'merge',
+        model.MERGER_MERGE_RESOLVE: 'merge',
+        model.MERGER_SQUASH_MERGE: 'squash'
     }
 
     def __init__(self, driver, connection, pipeline, config=None):
@@ -110,7 +109,7 @@ class GitlabReporter(BaseReporter):
         merge_mode = item.current_build_set.getMergeMode()
 
         if merge_mode not in self.merge_modes:
-            mode = [x[0] for x in MERGER_MAP.items() if x[1] == merge_mode][0]
+            mode = model.get_merge_mode_name(merge_mode)
             self.log.warning('Merge mode %s not supported by Gitlab', mode)
             raise MergeFailure('Merge mode %s not supported by Gitlab' % mode)
 
diff --git a/zuul/model.py b/zuul/model.py
index 97db54dea..4625abe22 100644
--- a/zuul/model.py
+++ b/zuul/model.py
@@ -123,6 +123,13 @@ def add_debug_line(debug_messages, msg, indent=0):
     debug_messages.append(indent + msg)
 
 
+def get_merge_mode_name(merge_mode):
+    "Look up the merge mode name given the constant"
+    for k, v in MERGER_MAP.items():
+        if v == merge_mode:
+            return k
+
+
 class ZuulMark:
     # The yaml mark class differs between the C and python versions.
     # The C version does not provide a snippet, and also appears to
diff --git a/zuul/web/__init__.py b/zuul/web/__init__.py
index 487c115c1..de8e91c2c 100755
--- a/zuul/web/__init__.py
+++ b/zuul/web/__init__.py
@@ -1241,10 +1241,7 @@ class ZuulWebAPI(object):
         result = project.toDict()
         result['configs'] = []
         md = tenant.layout.getProjectMetadata(project.canonical_name).toDict()
-        for k, v in model.MERGER_MAP.items():
-            if v == md['merge_mode']:
-                md['merge_mode'] = k
-                break
+        md['merge_mode'] = model.get_merge_mode_name(md['merge_mode'])
         result['metadata'] = md
         configs = tenant.layout.getAllProjectConfigs(project.canonical_name)
         for config_obj in configs: