Support inspection of computed column

Added support for reflection of "computed" columns, which are now returned
as part of the structure returned by :meth:`.Inspector.get_columns`.
When reflecting full :class:`.Table` objects, computed columns will
be represented using the :class:`.Computed` construct.

Also improve the documentation in :meth:`Inspector.get_columns`, correctly
listing all the returned keys.

Fixes: #5063
Fixes: #4051

Closes: #5064
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/5064
Pull-request-sha: ba00fc321ce468f8885aad23b3dd33c789e50fbe

Change-Id: I789986554fc8ac7f084270474d0b2c12046b1cc2

1 files changed, 23 insertions, 0 deletions

diff --git a/lib/sqlalchemy/testing/requirements.py b/lib/sqlalchemy/testing/requirements.py
index c12d1e6e8..5eb769bf3 100644
--- a/lib/sqlalchemy/testing/requirements.py
+++ b/lib/sqlalchemy/testing/requirements.py
@@ -1108,4 +1108,27 @@ class SuiteRequirements(Requirements):
 
     @property
     def computed_columns(self):
+        "Supports computed columns"
+        return exclusions.closed()
+
+    @property
+    def computed_columns_stored(self):
+        "Supports computed columns with `persisted=True`"
+        return exclusions.closed()
+
+    @property
+    def computed_columns_virtual(self):
+        "Supports computed columns with `persisted=False`"
+        return exclusions.closed()
+
+    @property
+    def computed_columns_default_persisted(self):
+        """If the default persistence is virtual or stored when `persisted`
+        is omitted"""
+        return exclusions.closed()
+
+    @property
+    def computed_columns_reflect_persisted(self):
+        """If persistence information is returned by the reflection of
+        computed columns"""
         return exclusions.closed()