From e67a03bbe37f15055e1ea22500565c262697109d Mon Sep 17 00:00:00 2001
From: Philipp Fischbeck <philipp.fischbeck@student.hpi.uni-potsdam.de>
Date: Sun, 1 Mar 2015 20:56:30 +0100
Subject: [PATCH] Add function for updating problem count

---
 app/models/problem.rb       |  9 +++++++++
 test/models/problem_test.rb | 17 +++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/app/models/problem.rb b/app/models/problem.rb
index 7747ddd..5bec039 100644
--- a/app/models/problem.rb
+++ b/app/models/problem.rb
@@ -15,4 +15,13 @@ class Problem < ActiveRecord::Base
   def original_url
     "https://projecteuler.net/problem=#{self.id}"
   end
+
+  def self.update_count(new_count)
+    old_count = Problem.count
+    raise ArgumentError, "new count has to be larger than old count" if new_count < old_count
+
+    new_count.times do |i|
+      Problem.where(id: i + 1).first_or_create!
+    end
+  end
 end
diff --git a/test/models/problem_test.rb b/test/models/problem_test.rb
index 595651f..67551ca 100644
--- a/test/models/problem_test.rb
+++ b/test/models/problem_test.rb
@@ -17,4 +17,21 @@ class ProblemTest < ActiveSupport::TestCase
   test "should have correct original url" do
     assert_equal "https://projecteuler.net/problem=1", problems(:one).original_url
   end
+
+  test "should allow for problem count updating" do
+    Problem.update_count(10)
+    assert_not Problem.where(id: 0).exists?
+    (1..10).each do |i|
+      assert Problem.where(id: i).exists?
+    end
+    assert_equal "First title", Problem.find(1).title
+  end
+
+  test "should not allow decreasing problem count update" do
+
+    assert_raises ArgumentError do
+      Problem.update_count(1)
+    end
+    assert_equal 3, Problem.count()
+  end
 end