Port erlang views tests into elixir test suite (#2237)

* Port erlang views tests into elixir test suite

* Enable erlang views in elixir testing

* Support nil or :null in response

4 files changed, 120 insertions, 3 deletions

diff --git a/Makefile b/Makefile
index 9bcd389be..0d4131aec 100644
--- a/Makefile
+++ b/Makefile
@@ -238,7 +238,7 @@ python-black-update: .venv/bin/black
 elixir: export MIX_ENV=integration
 elixir: export COUCHDB_TEST_ADMIN_PARTY_OVERRIDE=1
 elixir: elixir-init elixir-check-formatted elixir-credo devclean
-	@dev/run "$(TEST_OPTS)" -a adm:pass -n 1 --no-eval 'mix test --trace --exclude without_quorum_test --exclude with_quorum_test $(EXUNIT_OPTS)'
+	@dev/run "$(TEST_OPTS)" -a adm:pass -n 1 --enable-erlang-views --no-eval 'mix test --trace --exclude without_quorum_test --exclude with_quorum_test $(EXUNIT_OPTS)'
 
 .PHONY: elixir-init
 elixir-init: MIX_ENV=test
diff --git a/Makefile.win b/Makefile.win
index c74a54621..7278fec76 100644
--- a/Makefile.win
+++ b/Makefile.win
@@ -189,7 +189,7 @@ python-black-update: .venv/bin/black
 .PHONY: elixir
 elixir: export COUCHDB_TEST_ADMIN_PARTY_OVERRIDE=1
 elixir: elixir-init elixir-check-formatted elixir-credo devclean
-	@dev\run -a adm:pass --no-eval 'mix test --trace --exclude without_quorum_test --exclude with_quorum_test $(EXUNIT_OPTS)'
+	@dev\run -a adm:pass --enable-erlang-views --no-eval 'mix test --trace --exclude without_quorum_test --exclude with_quorum_test $(EXUNIT_OPTS)'
 
 .PHONY: elixir-init
 elixir-init:
diff --git a/test/elixir/README.md b/test/elixir/README.md
index 7c6b10e5a..7f13d8afc 100644
--- a/test/elixir/README.md
+++ b/test/elixir/README.md
@@ -45,7 +45,7 @@ X means done, - means partially
   - [ ] Port design_docs.js
   - [ ] Port design_options.js
   - [ ] Port design_paths.js
-  - [ ] Port erlang_views.js
+  - [X] Port erlang_views.js
   - [ ] Port etags_head.js
   - [ ] Port etags_views.js
   - [ ] Port form_submit.js
diff --git a/test/elixir/test/erlang_views_test.exs b/test/elixir/test/erlang_views_test.exs
new file mode 100644
index 000000000..3346c2274
--- /dev/null
+++ b/test/elixir/test/erlang_views_test.exs
@@ -0,0 +1,117 @@
+defmodule ErlangViewsTest do
+  use CouchTestCase
+
+  @moduletag :erlang_views
+
+  @moduledoc """
+  basic 'smoke tests' of erlang views.
+  This is a port of the erlang_views.js test suite.
+  """
+
+  @doc1 %{:_id => "1", :integer => 1, :string => "str1", :array => [1, 2, 3]}
+
+  @erlang_map_fun """
+   fun({Doc}) ->
+      K = couch_util:get_value(<<"integer">>, Doc, null),
+      V = couch_util:get_value(<<"string">>, Doc, null),
+      Emit(K, V)
+  end.
+  """
+
+  @erlang_reduce_fun """
+  fun (_, Values, false) -> length(Values);
+     (_, Values, true) -> lists:sum(Values)
+  end.
+  """
+
+  @erlang_map_fun_2 """
+  fun({Doc}) ->
+   Words = couch_util:get_value(<<"words">>, Doc),
+   lists:foreach(fun({Word}) ->
+     WordString = couch_util:get_value(<<"word">>, Word),
+     Count = couch_util:get_value(<<"count">>, Word),
+     Emit(WordString , Count)
+    end, Words)
+  end.
+  """
+
+  @erlang_reduce_fun_2 """
+  fun(Keys, Values, RR) -> length(Values) end.
+  """
+
+  @word_list ["foo", "bar", "abc", "def", "baz", "xxyz"]
+
+  @tag :with_db
+  test "Erlang map function", context do
+    db_name = context[:db_name]
+    create_doc(db_name, @doc1)
+
+    results =
+      query(
+        db_name,
+        @erlang_map_fun,
+        nil,
+        nil,
+        nil,
+        "erlang"
+      )
+
+    assert results["total_rows"] == 1
+    assert List.first(results["rows"])["key"] == 1
+    assert List.first(results["rows"])["value"] == "str1"
+  end
+
+  @tag :with_db
+  test "Erlang reduce function", context do
+    db_name = context[:db_name]
+    create_doc(db_name, @doc1)
+    doc2 = @doc1 |> Map.replace!(:_id, "2") |> Map.replace!(:string, "str2")
+    create_doc(db_name, doc2)
+
+    results =
+      query(
+        db_name,
+        @erlang_map_fun,
+        @erlang_reduce_fun,
+        nil,
+        nil,
+        "erlang"
+      )
+
+    assert List.first(results["rows"])["value"] == 2
+  end
+
+  @tag :with_db
+  test "Erlang reduce function larger dataset", context do
+    db_name = context[:db_name]
+    bulk_save(db_name, create_large_dataset(250))
+
+    results =
+      query(
+        db_name,
+        @erlang_map_fun_2,
+        @erlang_reduce_fun_2,
+        nil,
+        nil,
+        "erlang"
+      )
+
+    assert Map.get(List.first(results["rows"]), "key", :null) == :null
+    assert List.first(results["rows"])["value"] > 0
+  end
+
+  defp create_large_dataset(size) do
+    doc_words =
+      for j <- 0..100 do
+        %{word: get_word(j), count: j}
+      end
+
+    template_doc = %{words: doc_words}
+
+    make_docs(0..size, template_doc)
+  end
+
+  defp get_word(idx) do
+    Enum.at(@word_list, rem(idx, length(@word_list)))
+  end
+end