Adds tests for empty ignore files

test/dialyxir/formatter_test.exs

@@ -92,6 +92,27 @@ defmodule Dialyxir.FormatterTest do
       end)
     end
 
+    test "ignores an empty default ignore file" do
+      in_project(:ignore_default_empty, fn ->
+        {:ok, remaining,  :no_unused_filters} =
+          Formatter.format_and_filter([], Project, [], [IgnoreFileStrictFormatter])
+
+        assert Project.dialyzer_ignore_warnings() == nil
+        assert remaining == []
+      end)
+    end
+
+    test "ignores an empty ignore file specified in mix" do
+      in_project(:ignore_empty, fn ->
+        {:ok, remaining,  :no_unused_filters} =
+          Formatter.format_and_filter([], Project, [], [IgnoreFileStrictFormatter])
+
+        assert Project.dialyzer_ignore_warnings() == "ignore_empty_test.exs"
+        assert remaining == []
+      end)
+    end
+
+
     test "does not filter lines not matching the pattern" do
       warning =
         {:warn_return_no_exit, {~c"a/different_file.ex", 17},

test/fixtures/ignore_default_empty/mix.exs

@@ -0,0 +1,14 @@
+defmodule Ignore.Mixfile do
+  use Mix.Project
+
+  def project do
+    [
+      app: :ignore,
+      version: "0.1.0",
+      prune_code_paths: false,
+      dialyzer: [
+        list_unused_filters: true
+      ]
+    ]
+  end
+end

test/fixtures/ignore_empty/mix.exs

@@ -0,0 +1,15 @@
+defmodule Ignore.Mixfile do
+  use Mix.Project
+
+  def project do
+    [
+      app: :ignore,
+      version: "0.1.0",
+      prune_code_paths: false,
+      dialyzer: [
+        ignore_warnings: "ignore_empty_test.exs",
+        list_unused_filters: true
+      ]
+    ]
+  end
+end