CODEWITHSUNDEEP
c#.netunit-testing
Tomek
Tomek

Reputation: 741

Why Lists comparison fails, if lists are (seems to be) identical

my main target was to compare data stored in DB and in XLSX file.

To do that, I have two lists created following way:

private class ProductList
{
    public string productSku { get; set; }
    public string productName { get; set; }
    public string productSubfamilyId { get; set; }
    public string productSubfamilyName { get; set; }
    public string productFamilyId { get; set; }
    public string productFamilyName { get; set; }
};

(...)
List<ProductList> productListsDB = new List<ProductList>();
List<ProductList> productListsXLSX = new List<ProductList>();
(...)

To first one, I provide data directly from SQL query result:

while (reader.Read())
{
    ProductList pl = new ProductList();
    pl.productSku = reader.GetString(reader.GetOrdinal("ProductSku"));
    pl.productName = reader.GetString(reader.GetOrdinal("ProductName"));
    pl.productSubfamilyId = reader.GetString(reader.GetOrdinal("ProductSubfamilyId"));
    pl.productSubfamilyName = reader.GetString(reader.GetOrdinal("ProductSubfamilyName"));
    pl.productFamilyId = reader.GetString(reader.GetOrdinal("ProductFamilyId"));
    pl.productFamilyName = reader.GetString(reader.GetOrdinal("ProductFamilyName"));
    productListsDB.Add(pl);
}

Another one is filled with data stored in XLSX file:

for (int rowNum = startingRow; rowNum <= totalRows; rowNum++)
{
    var row = myWorksheet.Cells[rowNum, 1, rowNum, totalColumns].ToArray();

    ProductList pl = new ProductList();
    pl.productSku = (string)row[0].Value;
    pl.productName = (string)row[1].Value;
    pl.productSubfamilyId = (string)row[2].Value;
    pl.productSubfamilyName = (string)row[3].Value;
    pl.productFamilyId = (string)row[4].Value;
    pl.productFamilyName = (string)row[5].Value;
    productListsXLSX.Add(pl);
}

Then I wanted to compare them and:

Assert.IsTrue(Equals(productListsDB.Count,productListsXLSX.Count), "Number of records in Excel file and DB differs!");

Passes just fine!

But any of two following does NOT pass:

Assert.IsTrue(productListsDB.All(productListsXLSX.Contains), "Data sent in Excel file and stored in DB are equal.");
CollectionAssert.AreEquivalent(productListsDB, productListsXLSX, "Data sent in Excel file and stored in DB are equal.");

I'm pretty new to writing and debugging code, but I managed to get some insights of that lists with QuickWatch in VS. I copied data to separate files and compered them - they are identical:

http://pastebin.com/KFDHpQkC and http://pastebin.com/4j1n1nPH

Any clues guys?

Upvotes: 1

Views: 70

Answers (2)

Khanh TO
Khanh TO

Reputation: 48972

You need to override Equals to tell whether the 2 products are equivalent. Usually when we override Equals, we also override GetHashCode: Why is it important to override GetHashCode when Equals method is overridden?

private class ProductList
{
    public string productSku { get; set; }
    public string productName { get; set; }
    public string productSubfamilyId { get; set; }
    public string productSubfamilyName { get; set; }
    public string productFamilyId { get; set; }
    public string productFamilyName { get; set; }

    public override bool Equals(object otherProduct)
    {
        //your code goes here to tell when the 2 products are equivalent.
        //Here I assume that your 2 products are equal when all the properties are equal:
        if (otherProduct == null)
           return false;
        return this.productSku == otherProduct.productSku &&
               this.productName == otherProduct.productName &&
               this.productSubfamilyId == otherProduct.productSubfamilyId &&
               this.productSubfamilyName == otherProduct.productSubfamilyName &&
               this.productFamilyId == otherProduct.productFamilyId &&
               this.productFamilyName == otherProduct.productFamilyName;
    }

    public override int GetHashCode()
    {
         //return your hash code
         int hash = 13;
         hash = (hash * 7) + this.productSku.GetHashCode();
         hash = (hash * 7) + this.productName.GetHashCode();
         ...
         return hash;
    }
};

Upvotes: 2

user1672994
user1672994

Reputation: 10839

You have to override the Equals and GetHashCode methods. The Equals method will compare the property of first object to another object property.

Upvotes: 1

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