1 files changed, 47 insertions, 0 deletions
diff --git a/test/prism/ruby/source_test.rb b/test/prism/ruby/source_test.rb
new file mode 100644
index 0000000000..afd2825765
--- /dev/null
+++ b/test/prism/ruby/source_test.rb
@@ -0,0 +1,47 @@
+# frozen_string_literal: true
+
+require_relative "../test_helper"
+
+module Prism
+  class SourceTest < TestCase
+    def test_line_to_byte_offset
+      parse_result = Prism.parse(<<~SRC)
+      abcd
+      efgh
+      ijkl
+      SRC
+      source = parse_result.source
+
+      assert_equal 0, source.line_to_byte_offset(1)
+      assert_equal 5, source.line_to_byte_offset(2)
+      assert_equal 10, source.line_to_byte_offset(3)
+      assert_equal 15, source.line_to_byte_offset(4)
+      e = assert_raise(ArgumentError) { source.line_to_byte_offset(5) }
+      assert_equal "line 5 is out of range", e.message
+      e = assert_raise(ArgumentError) { source.line_to_byte_offset(0) }
+      assert_equal "line 0 is out of range", e.message
+      e = assert_raise(ArgumentError) { source.line_to_byte_offset(-1) }
+      assert_equal "line -1 is out of range", e.message
+    end
+
+    def test_line_to_byte_offset_with_start_line
+      parse_result = Prism.parse(<<~SRC, line: 11)
+      abcd
+      efgh
+      ijkl
+      SRC
+      source = parse_result.source
+
+      assert_equal 0, source.line_to_byte_offset(11)
+      assert_equal 5, source.line_to_byte_offset(12)
+      assert_equal 10, source.line_to_byte_offset(13)
+      assert_equal 15, source.line_to_byte_offset(14)
+      e = assert_raise(ArgumentError) { source.line_to_byte_offset(15) }
+      assert_equal "line 15 is out of range", e.message
+      e = assert_raise(ArgumentError) { source.line_to_byte_offset(10) }
+      assert_equal "line 10 is out of range", e.message
+      e = assert_raise(ArgumentError) { source.line_to_byte_offset(9) }
+      assert_equal "line 9 is out of range", e.message
+    end
+  end
+end