Engine: Add failing tests from Erubi test suite

test/engine/erubi_test_suite_test.rb

@@ -0,0 +1,88 @@
+# frozen_string_literal: true
+
+require_relative "../test_helper"
+require_relative "../../lib/herb/engine"
+
+# These tests are adapted from the erubi test suite at:
+# https://github.com/jeremyevans/erubi/blob/master/test/test.rb
+#
+# Each test verifies that Herb::Engine produces the exact same evaluated output
+# as Erubi::Engine for the given template and options.
+module Engine
+  class ErubiTestSuiteTest < Minitest::Spec
+    include SnapshotUtils
+
+    ERUBI_OPTS = { enforce_erubi_equality: true, enforce_actionview_erubi_equality: false }.freeze
+
+    test "handles literal erb escape with double percent" do
+      template = <<~'ERB'.chomp
+        <table>
+        <%% for item in @items %>
+          <tr>
+            <td><%# i+1 %></td>
+            <td><%# item %></td>
+          </tr>
+          <%% end %>
+        </table>
+      ERB
+
+      assert_evaluated_snapshot(template, { :@items => [2], i: 0 }, **ERUBI_OPTS)
+    end
+
+    test "double percent escapes erb tag" do
+      template = "<%%= 'literal' %>"
+
+      assert_evaluated_snapshot(template, {}, **ERUBI_OPTS)
+    end
+
+    test "double percent with equals escapes erb expression" do
+      template = "<%%== 'literal' %>"
+
+      assert_evaluated_snapshot(template, {}, **ERUBI_OPTS)
+    end
+
+    test "code tag with trailing content preserves whitespace" do
+      template = "  <% x = 1 %> b\n<%= x %>"
+
+      assert_evaluated_snapshot(template, {}, **ERUBI_OPTS)
+    end
+
+    test "trim false with code tags preserves whitespace" do
+      template = "  <% x = 1 %>\n<%= x %>\n"
+
+      assert_evaluated_snapshot(template, {}, trim: false, **ERUBI_OPTS)
+    end
+
+    test "trim false with comment tags preserves whitespace" do
+      template = "  <%# comment %>\ntext\n"
+
+      assert_evaluated_snapshot(template, {}, trim: false, **ERUBI_OPTS)
+    end
+
+    test "code tag with string containing erb-like content" do
+      template = "<% x = '<%' %><%= x %>"
+
+      assert_evaluated_snapshot(template, {}, **ERUBI_OPTS)
+    end
+
+    test "literal percent with different prefix and postfix" do
+      template = <<~'ERB'.chomp
+        <table>
+          <%% for item in @items %>
+          <tr>
+          </tr>
+          <%% end %>
+          <%%= "literal" %>
+        </table>
+      ERB
+
+      assert_evaluated_snapshot(
+        template,
+        { :@items => [2], i: 0 },
+        literal_prefix: "{%",
+        literal_postfix: "%}",
+        **ERUBI_OPTS
+      )
+    end
+  end
+end