Add "database config" field to Workspace.

This field specifies where to store the config created by ap_verify.

python/lsst/ap/verify/workspace.py

@@ -114,6 +114,15 @@ def dbLocation(self):
         Shall be a pathname to a database suitable for the backend of `Apdb`.
         """
 
+    @property
+    @abc.abstractmethod
+    def dbConfigLocation(self):
+        """The absolute location of the config file for the source association
+        database to be created or updated by the pipeline (`str`, read-only).
+
+        The location is assumed to be a Python (`lsst.pex.config.Config`) file.
+        """
+
     @property
     @abc.abstractmethod
     def alertLocation(self):
@@ -189,6 +198,10 @@ def pipelineDir(self):
     def dbLocation(self):
         return os.path.join(self._location, 'association.db')
 
+    @property
+    def dbConfigLocation(self):
+        return os.path.join(self._location, 'apdb.py')
+
     @property
     def alertLocation(self):
         return os.path.join(self._location, 'alerts')

tests/test_workspace.py

@@ -106,6 +106,15 @@ def testDatabase(self):
         # Workspace spec allows these to be URIs or paths, whatever the Butler accepts
         self._assertNotInDir(self._testbed.dbLocation, url2pathname(self._testbed.repo))
 
+    def testDbConfig(self):
+        """Verify that a WorkspaceGen3 requests a database config in the target
+        directory, but not in any repository.
+        """
+        root = self._testWorkspace
+        self._assertInDir(self._testbed.dbConfigLocation, root)
+        # Workspace spec allows these to be URIs or paths, whatever the Butler accepts
+        self._assertNotInDir(self._testbed.dbConfigLocation, url2pathname(self._testbed.repo))
+
     def testAlerts(self):
         """Verify that a WorkspaceGen3 requests an alert dump in the target
         directory, but not in any repository.