[GitHub] [couchdb] leo-pires commented on a change in pull request #2541: Port reduce_false.js and reduce_builtin.js to Elixir

[GitBox <gi...@apache.org>]

leo-pires commented on a change in pull request #2541: Port reduce_false.js and reduce_builtin.js to Elixir
URL: https://github.com/apache/couchdb/pull/2541#discussion_r378171202
 
 

 ##########
 File path: test/elixir/test/reduce_builtin_test.exs
 ##########
 @@ -0,0 +1,259 @@
+defmodule ReduceBultinTest do
+  use CouchTestCase
+
+  @moduletag :views
+
+  @moduledoc """
+  Test CouchDB view builtin reduce functions
+  This is a port of the reduce_builtin.js suite
+  """
+
+  def random_ddoc(db_name) do
+    "/#{db_name}/_design/#{:erlang.monotonic_time()}"
+  end
+
+  def summate(n) do
+    (n + 1) * n / 2
+  end
+
+  def sumsqr(n) do
+    1..n |> Enum.reduce(0, fn i, acc -> acc + i * i end)
+  end
+
+  def check_approx_distinct(expected, estimated) do
+    # see https://en.wikipedia.org/wiki/HyperLogLog
+    err = 1.04 / :math.sqrt(:math.pow(2, 11 - 1))
+    abs(expected - estimated) < expected * err
+  end
+
+  def query_rows(ddoc_url, builtin_fun, query \\ nil) do
+    http_opts = if query, do: [query: query], else: []
+    Couch.get("#{ddoc_url}/_view/builtin#{builtin_fun}", http_opts).body["rows"]
+  end
+  def query_value(ddoc_url, builtin_fun, query \\ nil) do
+    hd(query_rows(ddoc_url, builtin_fun, query))["value"]
+  end
+
+  @tag :with_db
+  test "Builtin reduce functions", context do
+    db_name = context[:db_name]
+    num_docs = 500
+
+    docs = make_docs(1..num_docs)
+    assert Couch.post("/#{db_name}/_bulk_docs", body: %{:docs => docs}, query: %{w: 3}).status_code in [
+             201,
+             202
+           ]
+
+    ddoc_url = random_ddoc(db_name)
+    map = ~s"""
+    function (doc) {
+      emit(doc.integer, doc.integer);
+      emit(doc.integer, doc.integer);
+    };
+    """
+    design_doc = %{:views => %{
+      :builtin_sum => %{:map => map, :reduce => "_sum"},
+      :builtin_count => %{:map => map, :reduce => "_count"},
+      :builtin_stats => %{:map => map, :reduce => "_stats"},
+      :builtin_approx_count_distinct => %{:map => map, :reduce => "_approx_count_distinct"}
+    }}
+    assert Couch.put(ddoc_url, body: design_doc).body["ok"]
+
+    value = ddoc_url |> query_value("_sum")
 
 Review comment:
   It's just idiomatics, being clearer that we're looking for a `_sum` here.

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