diff --git a/RhSolutions.AddIn/AddIn/RhSolutionsAddIn.cs b/RhSolutions.AddIn/AddIn/RhSolutionsAddIn.cs
index 38cea15..dcb0f7d 100644
--- a/RhSolutions.AddIn/AddIn/RhSolutionsAddIn.cs
+++ b/RhSolutions.AddIn/AddIn/RhSolutionsAddIn.cs
@@ -72,8 +72,8 @@ public sealed class RhSolutionsAddIn : IExcelAddIn
 
     public void AutoClose()
     {
-        EventsUtil.Uninitialize(); 
-        
+        EventsUtil.Uninitialize();
+
         bool isTesting = Environment.GetEnvironmentVariable("ISTESTING") switch
         {
             "true" => true,
diff --git a/RhSolutions.Tests/CanFillCouplings.cs b/RhSolutions.Tests/CanFillCouplings.cs
new file mode 100644
index 0000000..48e4ee8
--- /dev/null
+++ b/RhSolutions.Tests/CanFillCouplings.cs
@@ -0,0 +1,41 @@
+using RhSolutions.AddIn;
+
+namespace RhSolutions.Tests;
+
+[ExcelTestSettings(OutOfProcess = true)]
+public class CanFillCouplings : IDisposable
+{
+    private RhSolutionsAddIn _addIn;
+    private IFittingsCalculator _calculator;
+    private IReader _reader;
+    private IWriter _writer;
+    private Worksheet _worksheet;
+
+    public CanFillCouplings()
+    {
+        _addIn = new();
+        _addIn.AutoOpen();
+        _calculator = new CouplingsCalculator();
+        _reader = new ExcelReader(Util.Application, RhSolutionsAddIn.Configuration);
+        _writer = new CurrentPriceWriter(Util.Application, RhSolutionsAddIn.Configuration);
+        _worksheet = Util.Workbook.Worksheets[1];
+    }
+
+    [ExcelFact(Workbook = @"..\..\..\TestWorkbooks\TestSpecificationCouplings.xlsx")]
+    public void CanCalculateSleeves()
+    {
+        var products = _reader.ReadProducts(new[] { _worksheet });
+        var couplings = _calculator.Calculate(products.First().Item2);
+        _writer.WriteProducts(couplings);
+
+        Assert.Equal(7, _worksheet.Range["E2"].Value);
+        Assert.Equal(1, _worksheet.Range["E3"].Value);
+        Assert.Equal(1, _worksheet.Range["E5"].Value);
+        Assert.Equal(1, _worksheet.Range["E7"].Value);
+    }
+
+    public void Dispose()
+    {
+        _addIn.AutoClose();
+    }
+}
diff --git a/RhSolutions.Tests/TestWorkbooks/TestSpecificationCouplings.xlsx b/RhSolutions.Tests/TestWorkbooks/TestSpecificationCouplings.xlsx
new file mode 100644
index 0000000..0acdf22
Binary files /dev/null and b/RhSolutions.Tests/TestWorkbooks/TestSpecificationCouplings.xlsx differ