Add: Tags.get_builder_from_target_mount_point

3 files changed, 44 insertions, 5 deletions

diff --git a/vmdb/__init__.py b/vmdb/__init__.py
index 6913cfc..0b9ddc1 100644
--- a/vmdb/__init__.py
+++ b/vmdb/__init__.py
@@ -33,7 +33,16 @@ from .runcmd import (
     progress,
     error,
 )
-from .tags import Tags, UnknownTag, TagInUse, AlreadyHasDev, AlreadyHasFsType, AlreadyHasTargetMountPoint, AlreadyMounted
+from .tags import (
+    Tags,
+    UnknownTag,
+    TagInUse,
+    AlreadyHasDev,
+    AlreadyHasFsType,
+    AlreadyHasTargetMountPoint,
+    AlreadyMounted,
+    NeedBothMountPoints,
+)
 from .unmount import unmount, NotMounted
 from .spec import (
     Spec,
diff --git a/vmdb/tags.py b/vmdb/tags.py
index d774ec5..7cbae09 100644
--- a/vmdb/tags.py
+++ b/vmdb/tags.py
@@ -90,6 +90,12 @@ class Tags:
             raise AlreadyHasTargetMountPoint(tag)
         item['target_mount_point'] = target_mount_point
 
+    def get_builder_from_target_mount_point(self, target_mount_point):
+        for item in self._tags.values():
+            if item['target_mount_point'] == target_mount_point:
+                return item['builder_mount_point']
+        raise NeedBothMountPoints(target_mount_point)
+
     def _get(self, tag):
         item = self._tags.get(tag)
         if item is None:
@@ -131,3 +137,10 @@ class AlreadyHasTargetMountPoint(Exception):
 
     def __init__(self, tag):
         super().__init__('Already has target mount point: {}'.format(tag))
+
+
+class NeedBothMountPoints(Exception):
+
+    def __init__(self, target_mp):
+        super().__init__(
+            'Need both mount points set, target: {}'.format(target_mp))
diff --git a/vmdb/tags_tests.py b/vmdb/tags_tests.py
index 48d0b2a..29ca68e 100644
--- a/vmdb/tags_tests.py
+++ b/vmdb/tags_tests.py
@@ -46,7 +46,7 @@ class TagsTests(unittest.TestCase):
         with self.assertRaises(vmdb.UnknownTag):
             tags.get_dev('does-not-exist')
 
-    def test_get_mount_point_raises_error_for_unknown_tag(self):
+    def test_getting_builder_mount_point_raises_error_for_unknown_tag(self):
         tags = vmdb.Tags()
         with self.assertRaises(vmdb.UnknownTag):
             tags.get_builder_mount_point('does-not-exist')
@@ -65,7 +65,7 @@ class TagsTests(unittest.TestCase):
         self.assertEqual(tags.get_dev('first'), '/dev/foo')
         self.assertEqual(tags.get_builder_mount_point('first'), None)
 
-    def test_adds_mount_point(self):
+    def test_adds_builder_mount_point(self):
         tags = vmdb.Tags()
         tags.append('first')
         tags.set_builder_mount_point('first', '/mnt/foo')
@@ -73,13 +73,13 @@ class TagsTests(unittest.TestCase):
         self.assertEqual(tags.get_dev('first'), None)
         self.assertEqual(tags.get_builder_mount_point('first'), '/mnt/foo')
 
-    def test_mount_point_is_uncached_by_default(self):
+    def test_builder_mount_point_is_uncached_by_default(self):
         tags = vmdb.Tags()
         tags.append('first')
         tags.set_builder_mount_point('first', '/mnt/foo')
         self.assertFalse(tags.is_cached('first'))
 
-    def test_mount_point_can_be_made_cached(self):
+    def test_builder_mount_point_can_be_made_cached(self):
         tags = vmdb.Tags()
         tags.append('first')
         tags.set_builder_mount_point('first', '/mnt/foo', cached=True)
@@ -134,3 +134,20 @@ class TagsTests(unittest.TestCase):
         tags.set_target_mount_point('first', '/boot')
         with self.assertRaises(vmdb.AlreadyHasTargetMountPoint):
             tags.set_target_mount_point('first', '/')
+
+    def test_raises_error_if_both_mount_points_not_set(self):
+        tags = vmdb.Tags()
+        tags.append('first')
+        tags.set_target_mount_point('first', '/boot')
+        with self.assertRaises(vmdb.NeedBothMountPoints):
+            tags.get_builder_from_target_mount_point('/')
+
+    def test_returns_builder_when_given_target_mount_point(self):
+        tags = vmdb.Tags()
+        tags.append('first')
+        tags.set_builder_mount_point('first', '/mnt/foo')
+        tags.set_target_mount_point('first', '/boot')
+        self.assertEqual(
+            tags.get_builder_from_target_mount_point('/boot'),
+            '/mnt/foo'
+        )