selectin polymorphic loading

Added a new style of mapper-level inheritance loading
"polymorphic selectin".  This style of loading
emits queries for each subclass in an inheritance
hierarchy subsequent to the load of the base
object type, using IN to specify the desired
primary key values.

Fixes: #3948

Change-Id: I59e071c6142354a3f95730046e3dcdfc0e2c4de5

1 files changed, 35 insertions, 13 deletions

diff --git a/lib/sqlalchemy/testing/assertsql.py b/lib/sqlalchemy/testing/assertsql.py
index e39b6315d..86d850733 100644
--- a/lib/sqlalchemy/testing/assertsql.py
+++ b/lib/sqlalchemy/testing/assertsql.py
@@ -282,6 +282,32 @@ class AllOf(AssertRule):
             self.errormessage = list(self.rules)[0].errormessage
 
 
+class EachOf(AssertRule):
+
+    def __init__(self, *rules):
+        self.rules = list(rules)
+
+    def process_statement(self, execute_observed):
+        while self.rules:
+            rule = self.rules[0]
+            rule.process_statement(execute_observed)
+            if rule.is_consumed:
+                self.rules.pop(0)
+            elif rule.errormessage:
+                self.errormessage = rule.errormessage
+            if rule.consume_statement:
+                break
+
+        if not self.rules:
+            self.is_consumed = True
+
+    def no_more_statements(self):
+        if self.rules and not self.rules[0].is_consumed:
+            self.rules[0].no_more_statements()
+        elif self.rules:
+            super(EachOf, self).no_more_statements()
+
+
 class Or(AllOf):
 
     def process_statement(self, execute_observed):
@@ -319,24 +345,20 @@ class SQLAsserter(object):
         del self.accumulated
 
     def assert_(self, *rules):
-        rules = list(rules)
-        observed = list(self._final)
+        rule = EachOf(*rules)
 
-        while observed and rules:
-            rule = rules[0]
-            rule.process_statement(observed[0])
+        observed = list(self._final)
+        while observed:
+            statement = observed.pop(0)
+            rule.process_statement(statement)
             if rule.is_consumed:
-                rules.pop(0)
+                break
             elif rule.errormessage:
                 assert False, rule.errormessage
-
-            if rule.consume_statement:
-                observed.pop(0)
-
-        if not observed and rules:
-            rules[0].no_more_statements()
-        elif not rules and observed:
+        if observed:
             assert False, "Additional SQL statements remain"
+        elif not rule.is_consumed:
+            rule.no_more_statements()
 
 
 @contextlib.contextmanager