New dependencies not supported

To be done: #8

Author: dentarg

lib/parse_diff.rb

@@ -16,6 +16,6 @@ def self.parse(input)
       end
     end
 
-    versions
+    versions.select { |_gem_name, versions| versions.size == 2 }
   end
 end

test/fixtures/bigdecimal.diff

@@ -0,0 +1,16 @@
+diff --git a/Gemfile.lock b/Gemfile.lock
+index 180ed2c..d2b5691 100644
+--- a/Gemfile.lock
++++ b/Gemfile.lock
+@@ -1,8 +1,10 @@
+ GEM
+   remote: https://rubygems.org/
+   specs:
++    bigdecimal (3.1.4)
+     pg (1.2.3)
+-    sequel (5.39.0)
++    sequel (5.72.0)
++      bigdecimal
+ 
+ PLATFORMS
+   ruby

test/parse_diff_test.rb

@@ -5,7 +5,7 @@
 require_relative "../lib/parse_diff"
 
 class ParseDiffTest < Test::Unit::TestCase
-  def test_parse_diff
+  def test_multiple_bumps
     fixture  = File.join(__dir__, "fixtures", "sentry.diff")
     input    = File.read(fixture)
     expected = {
@@ -16,4 +16,14 @@ def test_parse_diff
 
     assert_equal expected, ParseDiff.parse(input)
   end
+
+  def test_only_added
+    fixture  = File.join(__dir__, "fixtures", "bigdecimal.diff")
+    input    = File.read(fixture)
+    expected = {
+      "sequel"  => %w[5.39.0 5.72.0],
+    }
+
+    assert_equal expected, ParseDiff.parse(input)
+  end
 end