set exception handler by request format, not always HTML

test/bdd/api/errors/formats.feature

@@ -0,0 +1,13 @@
+@APIDB
+Feature: Places by osm_type and osm_id Tests
+    Simple tests for errors in various response formats.
+
+    Scenario Outline: Force error by providing too many ids
+        When sending <format> lookup query for N1,N2,N3,N4,N5,N6,N7,N8,N9,N10,N11,N12,N13,N14,N15,N16,N17,N18,N19,N20,N21,N22,N23,N24,N25,N26,N27,N28,N29,N30,N31,N32,N33,N34,N35,N36,N37,N38,N39,N40,N41,N42,N43,N44,N45,N46,N47,N48,N49,N50,N51
+        Then a <format> user error is returned
+
+    Examples:
+        | format  |
+        | xml     |
+        | json    |
+        | geojson |

test/bdd/api/lookup/simple.feature

@@ -1,6 +1,6 @@
 @APIDB
 Feature: Places by osm_type and osm_id Tests
-    Simple tests for internal server errors and response format.
+    Simple tests for response format.
 
     Scenario Outline: address lookup for existing node, way, relation
         When sending <format> lookup query for N3284625766,W6065798,,R123924,X99,N0

test/bdd/api/search/simple.feature

@@ -194,7 +194,7 @@ Feature: Simple Tests
         When sending json search query "Tokyo"
             | param        | value |
             |json_callback | <data> |
-        Then a HTTP 400 is returned
+        Then a json user error is returned
 
     Examples:
       | data |

test/bdd/steps/queries.py

@@ -494,6 +494,18 @@ def step_impl(context, fmt):
     context.execute_steps("Then a HTTP 200 is returned")
     eq_(context.response.format, fmt)
 
+@then(u'a (?P<fmt>\w+) user error is returned')
+def check_page_error(context, fmt):
+    context.execute_steps("Then a HTTP 400 is returned")
+    eq_(context.response.format, fmt)
+
+    if fmt == 'html':
+        assert_is_not_none(re.search(r'<html( |>).+</html>', context.response.page, re.DOTALL))
+    elif fmt == 'xml':
+        assert_is_not_none(re.search(r'<error>.+</error>', context.response.page, re.DOTALL))
+    else:
+        assert_is_not_none(re.search(r'({"error":)', context.response.page, re.DOTALL))
+
 @then(u'result header contains')
 def check_header_attr(context):
     for line in context.table: