Allow storing attachments in compressed form. Closes COUCHDB-583. Thanks Filipe Manana

git-svn-id: https://svn.apache.org/repos/asf/couchdb/trunk@904650 13f79535-47bb-0310-9956-ffa450edef68

4 files changed, 580 insertions, 10 deletions

diff --git a/test/etap/030-doc-from-json.t b/test/etap/030-doc-from-json.t
index dc3327aa..359a75f9 100755
--- a/test/etap/030-doc-from-json.t
+++ b/test/etap/030-doc-from-json.t
@@ -17,7 +17,11 @@
 %% XXX: Figure out how to -include("couch_db.hrl")
 -record(doc, {id= <<"">>, revs={0, []}, body={[]},
             atts=[], deleted=false, meta=[]}).
--record(att, {name, type, len, md5= <<>>, revpos=0, data}).
+-record(att, {name, type, att_len, disk_len, md5= <<>>, revpos=0, data,
+            comp=false}).
+
+default_config() ->
+    test_util:build_file("etc/couchdb/default_dev.ini").
 
 main(_) ->
     test_util:init_code_path(),
@@ -32,6 +36,8 @@ main(_) ->
     ok.
 
 test() ->
+    couch_config:start_link([default_config()]),
+    couch_config:set("attachments", "compression_level", "0"),
     ok = test_from_json_success(),
     ok = test_from_json_errors(),
     ok.
@@ -85,13 +91,15 @@ test_from_json_success() ->
                     name = <<"my_attachment.fu">>,
                     data = stub,
                     type = <<"application/awesome">>,
-                    len = 45
+                    att_len = 45,
+                    disk_len = 45
                 },
                 #att{
                     name = <<"noahs_private_key.gpg">>,
                     data = <<"I have a pet fish!">>,
                     type = <<"application/pgp-signature">>,
-                    len = 18
+                    att_len = 18,
+                    disk_len = 18
                 }
             ]},
             "Attachments are parsed correctly."
diff --git a/test/etap/031-doc-to-json.t b/test/etap/031-doc-to-json.t
index 4e7a175f..89cf4bc9 100755
--- a/test/etap/031-doc-to-json.t
+++ b/test/etap/031-doc-to-json.t
@@ -17,7 +17,11 @@
 %% XXX: Figure out how to -include("couch_db.hrl")
 -record(doc, {id= <<"">>, revs={0, []}, body={[]},
             atts=[], deleted=false, meta=[]}).
--record(att, {name, type, len, md5= <<>>, revpos=0, data}).
+-record(att, {name, type, att_len, disk_len, md5= <<>>, revpos=0, data,
+            comp=false}).
+
+default_config() ->
+    test_util:build_file("etc/couchdb/default_dev.ini").
 
 main(_) ->
     test_util:init_code_path(),
@@ -32,6 +36,8 @@ main(_) ->
     ok.
 
 test() ->
+    couch_config:start_link([default_config()]),
+    couch_config:set("attachments", "compression_level", "0"),
     ok = test_to_json_success(),
     ok.
 
@@ -116,14 +122,16 @@ test_to_json_success() ->
                     type = <<"xml/sucks">>, 
                     data = fun() -> ok end,
                     revpos = 1,
-                    len = 400
+                    att_len = 400,
+                    disk_len = 400
                 },
                 #att{
                     name = <<"fast.json">>, 
                     type = <<"json/ftw">>, 
                     data = <<"{\"so\": \"there!\"}">>,
                     revpos = 1,
-                    len = 16
+                    att_len = 16,
+                    disk_len = 16
                 }
             ]},
             {[
@@ -153,7 +161,8 @@ test_to_json_success() ->
                     type = <<"text/plain">>,
                     data = fun() -> <<"diet pepsi">> end,
                     revpos = 1,
-                    len = 10
+                    att_len = 10,
+                    disk_len = 10
                 },
                 #att{
                     name = <<"food.now">>,
diff --git a/test/etap/050-stream.t b/test/etap/050-stream.t
index 9324916c..545dd524 100755
--- a/test/etap/050-stream.t
+++ b/test/etap/050-stream.t
@@ -42,7 +42,7 @@ test() ->
     etap:is(ok, couch_stream:write(Stream, <<>>),
         "Writing an empty binary does nothing."),
 
-    {Ptrs, Length, _} = couch_stream:close(Stream),
+    {Ptrs, Length, _, _, _} = couch_stream:close(Stream),
     etap:is(Ptrs, [0], "Close returns the file pointers."),
     etap:is(Length, 8, "Close also returns the number of bytes written."),
     etap:is(<<"foodfoob">>, read_all(Fd, Ptrs), "Returned pointers are valid."),
@@ -58,7 +58,7 @@ test() ->
     etap:is(ok, couch_stream:write(Stream2, ZeroBits),
         "Successfully wrote 80 0 bits."),
 
-    {Ptrs2, Length2, _} = couch_stream:close(Stream2),
+    {Ptrs2, Length2, _, _, _} = couch_stream:close(Stream2),
     etap:is(Ptrs2, [ExpPtr], "Closing stream returns the file pointers."),
     etap:is(Length2, 20, "Length written is 160 bytes."),
 
@@ -73,7 +73,7 @@ test() ->
         couch_stream:write(Stream3, Data),
         [Data | Acc]
     end, [], lists:seq(1, 1024)),
-    {Ptrs3, Length3, _} = couch_stream:close(Stream3),
+    {Ptrs3, Length3, _, _, _} = couch_stream:close(Stream3),
 
     % 4095 because of 5 * 4096 rem 5 (last write before exceeding threshold)
     % + 5 puts us over the threshold
diff --git a/test/etap/140-attachment-comp.t b/test/etap/140-attachment-comp.t
new file mode 100755
index 00000000..cb3039e6
--- /dev/null
+++ b/test/etap/140-attachment-comp.t
@@ -0,0 +1,553 @@
+#!/usr/bin/env escript
+%% -*- erlang -*-
+
+% Licensed under the Apache License, Version 2.0 (the "License"); you may not
+% use this file except in compliance with the License. You may obtain a copy of
+% the License at
+%
+%   http://www.apache.org/licenses/LICENSE-2.0
+%
+% Unless required by applicable law or agreed to in writing, software
+% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+% License for the specific language governing permissions and limitations under
+% the License.
+
+default_config() ->
+    test_util:build_file("etc/couchdb/default_dev.ini").
+
+test_db_name() ->
+    <<"couch_test_atts_compression">>.
+
+main(_) ->
+    test_util:init_code_path(),
+
+    etap:plan(57),
+    case (catch test()) of
+        ok ->
+            etap:end_tests();
+        Other ->
+            etap:diag(io_lib:format("Test died abnormally: ~p", [Other])),
+            etap:bail(Other)
+    end,
+    ok.
+
+test() ->
+    couch_server_sup:start_link([default_config()]),
+    put(addr, couch_config:get("httpd", "bind_address", "127.0.0.1")),
+    put(port, couch_config:get("httpd", "port", "5984")),
+    application:start(inets),
+    timer:sleep(1000),
+    couch_server:delete(test_db_name(), []),
+    couch_db:create(test_db_name(), []),
+
+    couch_config:set("attachments", "compression_level", "8"),
+    couch_config:set("attachments", "compressible_types", "text/*"),
+
+    create_1st_text_att(),
+    create_1st_png_att(),
+    create_2nd_text_att(),
+    create_2nd_png_att(),
+
+    tests_for_1st_text_att(),
+    tests_for_1st_png_att(),
+    tests_for_2nd_text_att(),
+    tests_for_2nd_png_att(),
+
+    timer:sleep(3000), % to avoid mochiweb socket closed exceptions
+    couch_server:delete(test_db_name(), []),
+    couch_server_sup:stop(),
+    ok.
+
+db_url() ->
+    "http://" ++ get(addr) ++ ":" ++ get(port) ++ "/" ++
+    binary_to_list(test_db_name()).
+
+create_1st_text_att() ->
+    {ok, {{_, Code, _}, _Headers, _Body}} = http:request(
+        put,
+        {db_url() ++ "/testdoc1/readme.txt", [],
+        "text/plain", test_text_data()},
+        [],
+        [{sync, true}]),
+    etap:is(Code, 201, "Created text attachment using the standalone api"),
+    ok.
+
+create_1st_png_att() ->
+    {ok, {{_, Code, _}, _Headers, _Body}} = http:request(
+        put,
+        {db_url() ++ "/testdoc2/icon.png", [],
+        "image/png", test_png_data()},
+        [],
+        [{sync, true}]),
+    etap:is(Code, 201, "Created png attachment using the standalone api"),
+    ok.
+
+% create a text attachment using the non-standalone attachment api
+create_2nd_text_att() ->
+    DocJson = {[
+        {<<"_attachments">>, {[
+            {<<"readme.txt">>, {[
+                {<<"content_type">>, <<"text/plain">>},
+                {<<"data">>, base64:encode(test_text_data())}
+            ]}
+        }]}}
+    ]},
+    {ok, {{_, Code, _}, _Headers, _Body}} = http:request(
+        put,
+        {db_url() ++ "/testdoc3", [],
+        "application/json", list_to_binary(couch_util:json_encode(DocJson))},
+        [],
+        [{sync, true}]),
+    etap:is(Code, 201, "Created text attachment using the non-standalone api"),
+    ok.
+
+% create a png attachment using the non-standalone attachment api
+create_2nd_png_att() ->
+    DocJson = {[
+        {<<"_attachments">>, {[
+            {<<"icon.png">>, {[
+                {<<"content_type">>, <<"image/png">>},
+                {<<"data">>, base64:encode(test_png_data())}
+            ]}
+        }]}}
+    ]},
+    {ok, {{_, Code, _}, _Headers, _Body}} = http:request(
+        put,
+        {db_url() ++ "/testdoc4", [],
+        "application/json", list_to_binary(couch_util:json_encode(DocJson))},
+        [],
+        [{sync, true}]),
+    etap:is(Code, 201, "Created png attachment using the non-standalone api"),
+    ok.
+
+tests_for_1st_text_att() ->
+    test_get_1st_text_att_with_accept_encoding_gzip(),
+    test_get_1st_text_att_without_accept_encoding_header(),
+    test_get_1st_text_att_with_accept_encoding_deflate(),
+    test_get_1st_text_att_with_accept_encoding_deflate_only(),
+    test_get_doc_with_1st_text_att(),
+    test_length_1st_text_att_stub().
+
+tests_for_1st_png_att() ->
+    test_get_1st_png_att_without_accept_encoding_header(),
+    test_get_1st_png_att_with_accept_encoding_gzip(),
+    test_get_1st_png_att_with_accept_encoding_deflate(),
+    test_get_doc_with_1st_png_att(),
+    test_length_1st_png_att_stub().
+
+tests_for_2nd_text_att() ->
+    test_get_2nd_text_att_with_accept_encoding_gzip(),
+    test_get_2nd_text_att_without_accept_encoding_header(),
+    test_get_doc_with_2nd_text_att(),
+    test_length_2nd_text_att_stub().
+
+tests_for_2nd_png_att() ->
+    test_get_2nd_png_att_without_accept_encoding_header(),
+    test_get_2nd_png_att_with_accept_encoding_gzip(),
+    test_get_doc_with_2nd_png_att(),
+    test_length_2nd_png_att_stub().
+
+test_get_1st_text_att_with_accept_encoding_gzip() ->
+    {ok, {{_, Code, _}, Headers, Body}} = http:request(
+        get,
+        {db_url() ++ "/testdoc1/readme.txt", [{"Accept-Encoding", "gzip"}]},
+        [],
+        [{sync, true}]),
+    etap:is(Code, 200, "HTTP response code is 200"),
+    Gziped = lists:member({"content-encoding", "gzip"}, Headers),
+    etap:is(Gziped, true, "received body is gziped"),
+    Uncompressed = binary_to_list(zlib:gunzip(list_to_binary(Body))),
+    etap:is(
+        Uncompressed,
+        test_text_data(),
+        "received data for the 1st text attachment is ok"
+    ),
+    ok.
+
+test_get_1st_text_att_without_accept_encoding_header() ->
+    {ok, {{_, Code, _}, Headers, Body}} = http:request(
+        get,
+        {db_url() ++ "/testdoc1/readme.txt", []},
+        [],
+        [{sync, true}]),
+    etap:is(Code, 200, "HTTP response code is 200"),
+    Gziped = lists:member({"content-encoding", "gzip"}, Headers),
+    etap:is(Gziped, false, "received body is not gziped"),
+    etap:is(
+        Body,
+        test_text_data(),
+        "received data for the 1st text attachment is ok"
+    ),
+    ok.
+
+test_get_1st_text_att_with_accept_encoding_deflate() ->
+    {ok, {{_, Code, _}, Headers, Body}} = http:request(
+        get,
+        {db_url() ++ "/testdoc1/readme.txt", [{"Accept-Encoding", "deflate"}]},
+        [],
+        [{sync, true}]),
+    etap:is(Code, 200, "HTTP response code is 200"),
+    Gziped = lists:member({"content-encoding", "gzip"}, Headers),
+    etap:is(Gziped, false, "received body is not gziped"),
+    Deflated = lists:member({"content-encoding", "deflate"}, Headers),
+    etap:is(Deflated, false, "received body is not deflated"),
+    etap:is(
+        Body,
+        test_text_data(),
+        "received data for the 1st text attachment is ok"
+    ),
+    ok.
+
+test_get_1st_text_att_with_accept_encoding_deflate_only() ->
+    {ok, {{_, Code, _}, _Headers, _Body}} = http:request(
+        get,
+        {db_url() ++ "/testdoc1/readme.txt",
+            [{"Accept-Encoding", "deflate, *;q=0"}]},
+        [],
+        [{sync, true}]),
+    etap:is(
+        Code,
+        406,
+        "HTTP response code is 406 for an unsupported content encoding request"
+    ),
+    ok.
+
+test_get_1st_png_att_without_accept_encoding_header() ->
+    {ok, {{_, Code, _}, Headers, Body}} = http:request(
+        get,
+        {db_url() ++ "/testdoc2/icon.png", []},
+        [],
+        [{sync, true}]),
+    etap:is(Code, 200, "HTTP response code is 200"),
+    Gziped = lists:member({"content-encoding", "gzip"}, Headers),
+    etap:is(Gziped, false, "received body is not gziped"),
+    etap:is(
+        Body,
+        test_png_data(),
+        "received data for the 1st png attachment is ok"
+    ),
+    ok.
+
+test_get_1st_png_att_with_accept_encoding_gzip() ->
+    {ok, {{_, Code, _}, Headers, Body}} = http:request(
+        get,
+        {db_url() ++ "/testdoc2/icon.png", [{"Accept-Encoding", "gzip"}]},
+        [],
+        [{sync, true}]),
+    etap:is(Code, 200, "HTTP response code is 200"),
+    Gziped = lists:member({"content-encoding", "gzip"}, Headers),
+    etap:is(Gziped, false, "received body is not gziped"),
+    etap:is(
+        Body,
+        test_png_data(),
+        "received data for the 1st png attachment is ok"
+    ),
+    ok.
+
+test_get_1st_png_att_with_accept_encoding_deflate() ->
+    {ok, {{_, Code, _}, Headers, Body}} = http:request(
+        get,
+        {db_url() ++ "/testdoc2/icon.png", [{"Accept-Encoding", "deflate"}]},
+        [],
+        [{sync, true}]),
+    etap:is(Code, 200, "HTTP response code is 200"),
+    Deflated = lists:member({"content-encoding", "deflate"}, Headers),
+    etap:is(Deflated, false, "received body is not deflated"),
+    Gziped = lists:member({"content-encoding", "gzip"}, Headers),
+    etap:is(Gziped, false, "received body is not gziped"),
+    etap:is(
+        Body,
+        test_png_data(),
+        "received data for the 1st png attachment is ok"
+    ),
+    ok.
+
+test_get_doc_with_1st_text_att() ->
+    {ok, {{_, Code, _}, _Headers, Body}} = http:request(
+        get,
+        {db_url() ++ "/testdoc1?attachments=true", []},
+        [],
+        [{sync, true}]),
+    etap:is(Code, 200, "HTTP response code is 200"),
+    Json = couch_util:json_decode(Body),
+    TextAttJson = couch_util:get_nested_json_value(
+        Json,
+        [<<"_attachments">>, <<"readme.txt">>]
+    ),
+    TextAttType = couch_util:get_nested_json_value(
+        TextAttJson,
+        [<<"content_type">>]
+    ),
+    TextAttData = couch_util:get_nested_json_value(
+        TextAttJson,
+        [<<"data">>]
+    ),
+    etap:is(
+        TextAttType,
+        <<"text/plain">>,
+        "1st text attachment has type text/plain"
+    ),
+    %% check the attachment's data is the base64 encoding of the plain text
+    %% and not the base64 encoding of the gziped plain text
+    etap:is(
+        TextAttData,
+        base64:encode(test_text_data()),
+        "1st text attachment data is properly base64 encoded"
+    ),
+    ok.
+
+test_length_1st_text_att_stub() ->
+    {ok, {{_, Code, _}, _Headers, Body}} = http:request(
+        get,
+        {db_url() ++ "/testdoc1", []},
+        [],
+        [{sync, true}]),
+    etap:is(Code, 200, "HTTP response code is 200"),
+    Json = couch_util:json_decode(Body),
+    TextAttJson = couch_util:get_nested_json_value(
+        Json,
+        [<<"_attachments">>, <<"readme.txt">>]
+    ),
+    TextAttLength = couch_util:get_nested_json_value(
+        TextAttJson,
+        [<<"length">>]
+    ),
+    etap:is(
+        TextAttLength,
+        length(test_text_data()),
+        "1st text attachment stub length matches the uncompressed length"
+    ),
+    ok.
+
+test_get_doc_with_1st_png_att() ->
+    {ok, {{_, Code, _}, _Headers, Body}} = http:request(
+        get,
+        {db_url() ++ "/testdoc2?attachments=true", []},
+        [],
+        [{sync, true}]),
+    etap:is(Code, 200, "HTTP response code is 200"),
+    Json = couch_util:json_decode(Body),
+    PngAttJson = couch_util:get_nested_json_value(
+        Json,
+        [<<"_attachments">>, <<"icon.png">>]
+    ),
+    PngAttType = couch_util:get_nested_json_value(
+        PngAttJson,
+        [<<"content_type">>]
+    ),
+    PngAttData = couch_util:get_nested_json_value(
+        PngAttJson,
+        [<<"data">>]
+    ),
+    etap:is(PngAttType, <<"image/png">>, "attachment has type image/png"),
+    etap:is(
+        PngAttData,
+        base64:encode(test_png_data()),
+        "1st png attachment data is properly base64 encoded"
+    ),
+    ok.
+
+test_length_1st_png_att_stub() ->
+    {ok, {{_, Code, _}, _Headers, Body}} = http:request(
+        get,
+        {db_url() ++ "/testdoc2", []},
+        [],
+        [{sync, true}]),
+    etap:is(Code, 200, "HTTP response code is 200"),
+    Json = couch_util:json_decode(Body),
+    PngAttJson = couch_util:get_nested_json_value(
+        Json,
+        [<<"_attachments">>, <<"icon.png">>]
+    ),
+    PngAttLength = couch_util:get_nested_json_value(
+        PngAttJson,
+        [<<"length">>]
+    ),
+    etap:is(
+        PngAttLength,
+        length(test_png_data()),
+        "1st png attachment stub length matches the uncompressed length"
+    ),
+    ok.
+
+test_get_2nd_text_att_with_accept_encoding_gzip() ->
+    {ok, {{_, Code, _}, Headers, Body}} = http:request(
+        get,
+        {db_url() ++ "/testdoc3/readme.txt", [{"Accept-Encoding", "gzip"}]},
+        [],
+        [{sync, true}]),
+    etap:is(Code, 200, "HTTP response code is 200"),
+    Gziped = lists:member({"content-encoding", "gzip"}, Headers),
+    etap:is(Gziped, true, "received body is gziped"),
+    Uncompressed = binary_to_list(zlib:gunzip(list_to_binary(Body))),
+    etap:is(
+        Uncompressed,
+        test_text_data(),
+        "received data for the 2nd text attachment is ok"
+    ),
+    ok.
+
+test_get_2nd_text_att_without_accept_encoding_header() ->
+    {ok, {{_, Code, _}, Headers, Body}} = http:request(
+        get,
+        {db_url() ++ "/testdoc3/readme.txt", []},
+        [],
+        [{sync, true}]),
+    etap:is(Code, 200, "HTTP response code is 200"),
+    Gziped = lists:member({"content-encoding", "gzip"}, Headers),
+    etap:is(Gziped, false, "received body is not gziped"),
+    etap:is(
+        Body,
+        test_text_data(),
+        "received data for the 2nd text attachment is ok"
+    ),
+    ok.
+
+test_get_2nd_png_att_without_accept_encoding_header() ->
+    {ok, {{_, Code, _}, Headers, Body}} = http:request(
+        get,
+        {db_url() ++ "/testdoc4/icon.png", []},
+        [],
+        [{sync, true}]),
+    etap:is(Code, 200, "HTTP response code is 200"),
+    Gziped = lists:member({"content-encoding", "gzip"}, Headers),
+    etap:is(Gziped, false, "received body is not gziped"),
+    etap:is(
+        Body,
+        test_png_data(),
+        "received data for the 2nd png attachment is ok"
+    ),
+    ok.
+
+test_get_2nd_png_att_with_accept_encoding_gzip() ->
+    {ok, {{_, Code, _}, Headers, Body}} = http:request(
+        get,
+        {db_url() ++ "/testdoc4/icon.png", [{"Accept-Encoding", "gzip"}]},
+        [],
+        [{sync, true}]),
+    etap:is(Code, 200, "HTTP response code is 200"),
+    Gziped = lists:member({"content-encoding", "gzip"}, Headers),
+    etap:is(Gziped, false, "received body is not gziped"),
+    etap:is(
+        Body,
+        test_png_data(),
+        "received data for the 2nd png attachment is ok"
+    ),
+    ok.
+
+test_get_doc_with_2nd_text_att() ->
+    {ok, {{_, Code, _}, _Headers, Body}} = http:request(
+        get,
+        {db_url() ++ "/testdoc3?attachments=true", []},
+        [],
+        [{sync, true}]),
+    etap:is(Code, 200, "HTTP response code is 200"),
+    Json = couch_util:json_decode(Body),
+    TextAttJson = couch_util:get_nested_json_value(
+        Json,
+        [<<"_attachments">>, <<"readme.txt">>]
+    ),
+    TextAttType = couch_util:get_nested_json_value(
+        TextAttJson,
+        [<<"content_type">>]
+    ),
+    TextAttData = couch_util:get_nested_json_value(
+        TextAttJson,
+        [<<"data">>]
+    ),
+    etap:is(TextAttType, <<"text/plain">>, "attachment has type text/plain"),
+    %% check the attachment's data is the base64 encoding of the plain text
+    %% and not the base64 encoding of the gziped plain text
+    etap:is(
+        TextAttData,
+        base64:encode(test_text_data()),
+        "2nd text attachment data is properly base64 encoded"
+    ),
+    ok.
+
+test_length_2nd_text_att_stub() ->
+    {ok, {{_, Code, _}, _Headers, Body}} = http:request(
+        get,
+        {db_url() ++ "/testdoc3", []},
+        [],
+        [{sync, true}]),
+    etap:is(Code, 200, "HTTP response code is 200"),
+    Json = couch_util:json_decode(Body),
+    TextAttJson = couch_util:get_nested_json_value(
+        Json,
+        [<<"_attachments">>, <<"readme.txt">>]
+    ),
+    TextAttLength = couch_util:get_nested_json_value(
+        TextAttJson,
+        [<<"length">>]
+    ),
+    etap:is(
+        TextAttLength,
+        length(test_text_data()),
+        "2nd text attachment stub length matches the uncompressed length"
+    ),
+    ok.
+
+test_get_doc_with_2nd_png_att() ->
+    {ok, {{_, Code, _}, _Headers, Body}} = http:request(
+        get,
+        {db_url() ++ "/testdoc4?attachments=true", []},
+        [],
+        [{sync, true}]),
+    etap:is(Code, 200, "HTTP response code is 200"),
+    Json = couch_util:json_decode(Body),
+    PngAttJson = couch_util:get_nested_json_value(
+        Json,
+        [<<"_attachments">>, <<"icon.png">>]
+    ),
+    PngAttType = couch_util:get_nested_json_value(
+        PngAttJson,
+        [<<"content_type">>]
+    ),
+    PngAttData = couch_util:get_nested_json_value(
+        PngAttJson,
+        [<<"data">>]
+    ),
+    etap:is(PngAttType, <<"image/png">>, "attachment has type image/png"),
+    etap:is(
+        PngAttData,
+        base64:encode(test_png_data()),
+        "2nd png attachment data is properly base64 encoded"
+    ),
+    ok.
+
+test_length_2nd_png_att_stub() ->
+    {ok, {{_, Code, _}, _Headers, Body}} = http:request(
+        get,
+        {db_url() ++ "/testdoc4", []},
+        [],
+        [{sync, true}]),
+    etap:is(Code, 200, "HTTP response code is 200"),
+    Json = couch_util:json_decode(Body),
+    PngAttJson = couch_util:get_nested_json_value(
+        Json,
+        [<<"_attachments">>, <<"icon.png">>]
+    ),
+    PngAttLength = couch_util:get_nested_json_value(
+        PngAttJson,
+        [<<"length">>]
+    ),
+    etap:is(
+        PngAttLength,
+        length(test_png_data()),
+        "2nd png attachment stub length matches the uncompressed length"
+    ),
+    ok.
+
+test_png_data() ->
+    {ok, Data} = file:read_file(
+        test_util:source_file("share/www/image/logo.png")
+    ),
+    binary_to_list(Data).
+
+test_text_data() ->
+    {ok, Data} = file:read_file(
+        test_util:source_file("README")
+    ),
+    binary_to_list(Data).