test: cover CorsArticlesController, show and CsrfTest

test/test_csrf.rb

@@ -0,0 +1,51 @@
+require 'minitest/autorun'
+require 'prism'
+
+class CsrfTest < Minitest::Test
+  def setup
+    @session = {}
+    @csrf = Prism::Csrf.new(@session)
+  end
+
+  def test_raw_token_is_persisted_in_session
+    token = @csrf.raw_token
+    assert_equal token, @session[Prism::Csrf::SESSION_KEY]
+  end
+
+  def test_raw_token_is_stable_across_calls
+    assert_equal @csrf.raw_token, @csrf.raw_token
+  end
+
+  def test_masked_token_differs_each_call
+    refute_equal @csrf.masked_token, @csrf.masked_token
+  end
+
+  def test_masked_token_is_valid
+    assert @csrf.valid_token?(@csrf.masked_token)
+  end
+
+  def test_multiple_masked_tokens_from_same_raw_token_all_validate
+    tokens = Array.new(5) { @csrf.masked_token }
+    assert tokens.all? { |token| @csrf.valid_token?(token) }
+    assert_equal 5, tokens.uniq.size
+  end
+
+  def test_token_from_different_session_is_rejected
+    other_session = {}
+    other_csrf = Prism::Csrf.new(other_session)
+    refute @csrf.valid_token?(other_csrf.masked_token)
+  end
+
+  def test_blank_or_garbage_tokens_are_rejected
+    refute @csrf.valid_token?(nil)
+    refute @csrf.valid_token?('')
+    refute @csrf.valid_token?('not-base64!!!')
+    refute @csrf.valid_token?('dGhpcyBpcyB0b28gc2hvcnQ=')
+  end
+
+  def test_tampering_with_masked_token_invalidates_it
+    masked = @csrf.masked_token
+    tampered = masked.sub(/.\z/) { |c| c == 'a' ? 'b' : 'a' }
+    refute @csrf.valid_token?(tampered)
+  end
+end