#398

backend/spec/services/preview/http_fetcher_spec.rb

@@ -0,0 +1,23 @@
+require 'rails_helper'
+
+RSpec.describe Preview::HttpFetcher do
+  describe '.fetch' do
+    it 'raises FetchFailed when redirect location is invalid' do
+      redirect = Net::HTTPFound.new('1.1', '302', 'Found')
+      redirect['location'] = 'http://[invalid'
+
+      allow(Preview::UrlSafety).to receive(:validate)
+          .with('https://example.com/page')
+          .and_return([URI.parse('https://example.com/page'), ['203.0.113.10']])
+      allow(described_class).to receive(:request)
+          .and_return(redirect)
+      allow(Rails.logger).to receive(:warn)
+
+      expect {
+        described_class.fetch('https://example.com/page')
+      }.to raise_error(Preview::HttpFetcher::FetchFailed)
+      expect(Rails.logger).to have_received(:warn)
+          .with(/invalid_redirect_location/)
+    end
+  end
+end

backend/spec/services/preview/thumbnail_fetcher_spec.rb

@@ -0,0 +1,51 @@
+require 'rails_helper'
+
+RSpec.describe Preview::ThumbnailFetcher do
+  describe '.fetch' do
+    it 'rejects svg thumbnails' do
+      page = Preview::HttpFetcher::Response.new(
+          '<meta property="og:image" content="https://example.com/thumb.svg">',
+          'text/html',
+          'https://example.com/page')
+      svg = Preview::HttpFetcher::Response.new(
+          '<svg></svg>',
+          'image/svg+xml',
+          'https://example.com/thumb.svg')
+
+      allow(Preview::UrlSafety).to receive(:validate)
+          .and_return([URI.parse('https://example.com/page'), ['203.0.113.10']])
+      allow(Preview::HttpFetcher).to receive(:fetch)
+          .with('https://example.com/page', max_bytes: described_class::HTML_MAX_BYTES)
+          .and_return(page)
+      allow(Preview::HttpFetcher).to receive(:fetch)
+          .with('https://example.com/thumb.svg')
+          .and_return(svg)
+
+      expect {
+        described_class.fetch('https://example.com/page')
+      }.to raise_error(Preview::ThumbnailFetcher::GenerationFailed)
+    end
+
+    it 'accepts allowed image content type with parameters' do
+      page = Preview::HttpFetcher::Response.new(
+          '<meta property="og:image" content="https://example.com/thumb.jpg">',
+          'text/html',
+          'https://example.com/page')
+      image = Preview::HttpFetcher::Response.new(
+          'jpeg-bytes',
+          'image/jpeg; charset=binary',
+          'https://example.com/thumb.jpg')
+
+      allow(Preview::UrlSafety).to receive(:validate)
+          .and_return([URI.parse('https://example.com/page'), ['203.0.113.10']])
+      allow(Preview::HttpFetcher).to receive(:fetch)
+          .with('https://example.com/page', max_bytes: described_class::HTML_MAX_BYTES)
+          .and_return(page)
+      allow(Preview::HttpFetcher).to receive(:fetch)
+          .with('https://example.com/thumb.jpg')
+          .and_return(image)
+
+      expect(described_class.fetch('https://example.com/page')).to eq('jpeg-bytes')
+    end
+  end
+end

backend/spec/services/preview/url_safety_spec.rb

@@ -0,0 +1,15 @@
+require 'rails_helper'
+
+RSpec.describe Preview::UrlSafety do
+  describe '.validate' do
+    it 'raises UnsafeUrl when DNS resolution fails' do
+      allow(Resolv).to receive(:getaddresses)
+          .with('missing.example')
+          .and_raise(Resolv::ResolvError)
+
+      expect {
+        described_class.validate('https://missing.example')
+      }.to raise_error(Preview::UrlSafety::UnsafeUrl)
+    end
+  end
+end