lib/esv.rb in excel-esv-0.0.3 vs lib/esv.rb in excel-esv-0.0.4

@@ -11,8 +11,14 @@
   end
 
   def self.parse(data)
     fake_file = StringIO.new(data)
     book = Spreadsheet.open(fake_file)
+
+    # We could support multiple worksheets, but let's not until we actually need it.
+    # Until then, we prefer raising to silently ignoring worksheets.
+    worksheet_count = book.worksheets.length
+    raise "Expected 1 worksheet, found #{worksheet_count}." if worksheet_count > 1
+
     book.worksheet(0).to_a
   end
 end