test: add template, view, session, and flash tests

test/test_template.rb

@@ -0,0 +1,29 @@
+require 'minitest/autorun'
+require 'prism'
+
+class TemplateTest < Minitest::Test
+  def test_interpolation
+    assert_equal 'Hello, Ruby!', Prism::Template.render('Hello, <%= name %>!', name: 'Ruby')
+  end
+
+  def test_html_escape
+    result = Prism::Template.render('<%= value %>', value: '<script>alert(1)</script>')
+    assert_equal '&lt;script&gt;alert(1)&lt;/script&gt;', result
+  end
+
+  def test_raw_output
+    result = Prism::Template.render('<%== value %>', value: '<b>bold</b>')
+    assert_equal '<b>bold</b>', result
+  end
+
+  def test_logic
+    template = '<% items.each do |n| %><%= n %>;<% end %>'
+    assert_equal '1;2;3;', Prism::Template.render(template, items: [1, 2, 3])
+  end
+
+  def test_conditional
+    template = '<% if admin %>yes<% else %>no<% end %>'
+    assert_equal 'yes', Prism::Template.render(template, admin: true)
+    assert_equal 'no', Prism::Template.render(template, admin: false)
+  end
+end