test: cover CorsArticlesController, show and CsrfTest

test/test_cors_conditional_get.rb

@@ -0,0 +1,90 @@
+require 'minitest/autorun'
+require 'prism'
+require 'support'
+
+# Session 52's documented debt: Cors and ConditionalGet were each tested in
+# isolation, but never together - and the two subsystems interact in a way
+# that is easy to get wrong. Prism::Middleware::Cors stamps headers onto
+# whatever [status, headers, body] the app below it returns
+# (lib/prism/middleware/cors.rb#call), without special-casing any status
+# code, and Controller#halt(304, '') (used by fresh_when/stale?) short-
+# circuits rendering but still returns through the SAME response path as a
+# normal 200 - so a cross-origin conditional GET that turns out fresh
+# should still come back as a CORS-tagged 304 with an empty body, not lose
+# its Access-Control-* headers just because nothing was actually rendered.
+class CorsArticlesController < Prism::Controller
+  ETAG = 'cors-article-v1'.freeze
+
+  def show
+    fresh_when(etag: ETAG)
+    html('full article body')
+  end
+end
+
+class CorsConditionalGetApp < Prism::Application
+  get '/api/articles/1', to: 'cors_articles#show'
+end
+
+class CorsConditionalGetTest < Minitest::Test
+  include TestSupport
+
+  ORIGIN = 'https://app.example.com'.freeze
+  FRESH_ETAG = 'W/"' + Digest::SHA1.hexdigest(CorsArticlesController::ETAG) + '"'
+
+  def setup
+    Prism::Cors.reset!
+    Prism::Cors.configure do |config|
+      config.allow do
+        origins ORIGIN
+        resource '/api/*', methods: %w[GET]
+      end
+    end
+    @app = Prism::Middleware::Cors.new(CorsConditionalGetApp)
+  end
+
+  def teardown
+    Prism::Cors.reset!
+  end
+
+  def call(headers)
+    @app.call(env_for('GET', '/api/articles/1', headers: headers))
+  end
+
+  def test_first_cross_origin_request_renders_and_still_gets_cors_headers
+    status, headers, body = call('Origin' => ORIGIN)
+
+    assert_equal 200, status
+    assert_equal 'full article body', body.join
+    assert_equal FRESH_ETAG, headers['ETag']
+    assert_equal ORIGIN, headers['Access-Control-Allow-Origin']
+    assert_equal 'Origin', headers['Vary']
+  end
+
+  def test_fresh_cross_origin_request_gets_304_with_cors_headers_intact
+    status, headers, body = call('Origin' => ORIGIN, 'If-None-Match' => FRESH_ETAG)
+
+    assert_equal 304, status
+    assert_equal '', body.join
+    assert_equal FRESH_ETAG, headers['ETag'], 'ETag must still be set on a 304, the client needs it to keep caching'
+    assert_equal ORIGIN, headers['Access-Control-Allow-Origin'],
+                 'a 304 short-circuited by halt() must not lose the CORS headers Cors already knows to stamp on any status'
+    assert_equal 'Origin', headers['Vary']
+  end
+
+  def test_fresh_same_origin_request_gets_304_without_cors_headers
+    status, headers, body = call('If-None-Match' => FRESH_ETAG)
+
+    assert_equal 304, status
+    assert_equal '', body.join
+    assert_equal FRESH_ETAG, headers['ETag']
+    assert_nil headers['Access-Control-Allow-Origin']
+  end
+
+  def test_stale_cross_origin_request_from_a_disallowed_origin_still_renders_without_cors_headers
+    status, headers, body = call('Origin' => 'https://evil.example.com', 'If-None-Match' => FRESH_ETAG)
+
+    assert_equal 304, status, 'ConditionalGet does not know or care about CORS - freshness alone decides the status'
+    assert_equal '', body.join
+    assert_nil headers['Access-Control-Allow-Origin']
+  end
+end