Category Archives: Code

Software Development

NUnit Constraints Example – a Simple Custom Constraint

Are you short of an NUnit Assertion? You have some code for a test, but you really want it in NUnit constraint form so you can use it like any other test. They are easy to write. Here’s an example which wraps a function you already wrote as a Constraint:

public class EqualsByValueConstraint : Constraint
{
	private readonly object expected;
	private CompareResult compareResult;

	public EqualsByValueConstraint(object expected)
	{
		this.expected = expected;
	}

	public override bool Matches(object actual)
	{
		this.actual = actual;
		compareResult = EqualsByValueOrFailureReason(actual, expected);
		return compareResult;
	}

	public override void WriteDescriptionTo(MessageWriter writer)
	{
		writer.WriteExpectedValue(this.expected);
	}
	public override void WriteActualValueTo(MessageWriter writer)
	{
		base.WriteActualValueTo(writer);
		writer.WriteLine();
		writer.WriteMessageLine("Compare Result " + compareResult);
	}
}
public class CompareResult
{
	public bool IsPass {get;set;}
	public string FailureDescription {get; set;}
}

If your function is just a boolean, then you could remove the CompareResult class. The drawback being that your failure message will only say ‘failed’ rather than give an explanation of the failure. In that case, you might just as well not use the constraint and use the Assert.That(bool, message) overload.

A Very Small Editable PDF for Testing

A Small PDF

Ever wanted a small PDF file, or to tweak your own PDF for testing? Below is a very small PDF which you can paste into a text editor and save as MySmallPdf.PDF.
Two things are easy to edit:

  • The page size. Look for the line /MediaBox [0 0 612 144]. Leave the first (0,0) pair and edit the (612,144) to be (width of page,height of page) in 1/72ths of an inch.
  • One line of text. Look for the line (This is a small text editable pdf) Tj and replace the text with your own.

This is particularly helpful if you are testing http://itextpdf.com/ or itextsharp or some other PDF generator or API, and you want a couple of small identifiable test files to play with.

The Editable PDF

%PDF-1.4
1 0 obj
<< /Type /Catalog
/Outlines 2 0 R
/Pages 3 0 R
>>
endobj
2 0 obj
<< /Type /Outlines
/Count 0
>>
endobj
3 0 obj
<< /Type /Pages
/Kids [4 0 R]
/Count 1
>>
endobj
4 0 obj
<< /Type /Page
/Parent 3 0 R
/MediaBox [0 0 612 144]
/Contents 5 0 R
/Resources << /ProcSet 6 0 R
/Font << /F1 7 0 R >>
>>
>>
endobj
5 0 obj
<< /Length 73 >>
stream
BT
/F1 24 Tf
100 100 Td
(This is a small text editable pdf) Tj
ET
endstream
endobj
6 0 obj
[/PDF /Text]
endobj
7 0 obj
<< /Type /Font
/Subtype /Type1
/Name /F1
/BaseFont /Helvetica
/Encoding /MacRomanEncoding
>>
endobj
xref
0 8
0000000000 65535 f
0000000009 00000 n
0000000074 00000 n
0000000120 00000 n
0000000179 00000 n
0000000364 00000 n
0000000466 00000 n
0000000496 00000 n
trailer
<< /Size 8
/Root 1 0 R
>>
startxref
625
%%EOF

The PDF ISO32000 standard

The PDF reference is available for free from Adobe at http://www.adobe.com/content/dotcom/en/devnet/pdf/pdf_reference.html The one you want is the copy of the ISO reference at http://wwwimages.adobe.com/www.adobe.com/content/dam/Adobe/en/devnet/pdf/pdfs/PDF32000_2008.pdf

Sending large byte[] of binary data through WCF – a simple approach

You can send large streams of data through WCF in two ways: by streaming or by buffer. How to enable streaming is discussed here but has the significant restriction that if you stream, you can only have one (yes, 1) parameter into and out of the service. If your goal is just to pass largish objects such as a spreadsheet or a PDF as part of a service operation this could be a significant hurdle to code around.

“By buffer” means that your large data can be handled with no special treatment at all: it is sent, read into memory (the buffer), and processed just like small messages are. You must understand that buffering means the whole message is buffered; As of early 21st century, that fine on most servers for muliti-megabyte data, but not fine for gigabytes of data.

The simple way to handles megabyte messages is to create a binding Configuration with 2 or 3 parameters increased:

  <system.serviceModel>
    <bindings>
      <basicHttpBinding>
        <binding name="basicHttpFor2MBMessage" maxBufferSize="2097152" maxReceivedMessageSize="2097152">
          <readerQuotas maxArrayLength="2097000" />
        </binding>
      </basicHttpBinding>
    </bindings>

and have your service endpoint use it:

<endpoint address="" binding="basicHttpBinding" bindingConfiguration="basicHttpFor2MBMessage" contract="yourContractName>

Voila. You can now send a 2MB large array through SOAP to WCF.

If your large array is binary data, you declare it in your service classes as byte[], which is why you need the maxArrayLength setting. If you are creating test messages by hand or in a testing tool, you also need to know how to represent binary data in a SOAP message.
The usual answer is, use base64 encoding and it should just work, thus:

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:dat="http://MyServiceName">
   <soapenv:Header/>
   <soapenv:Body>
      <dat:Save>
         <dat:Id>111</dat:applicantId>
         <dat:Pdf>JVBE ... <i>base64 encoded string</i> .... JUVPRgo=</dat:contractPdf>
      </dat:Save>
   </soapenv:Body>
</soapenv:Envelope>

Caveats

Security

The WCF default small buffer and message sizes are a guard against DoS attacks so if your service is publicly visible this would leave it less well guarded.

Performance

How fast does your service process large requests?

If (Expected Peak Requests Per Minute) * (Seconds to Process a Request) is bigger than 60 (Seconds in a Minute) then you need more horsepower.

How much memory do you have?

If (Size of Message * Requests per Hour) – (Speed at which WCF frees up an hour’s worth of used buffers) is bigger than your available memory then you’ll fall over. Alas there is no simple setting for ‘Speed at which WCF frees up an hour’s worth of used buffers’ so that calculation is a problem for another blog post. If you might have a problem, you can use PerfMon to watch memory behaviour during a stress test.

dotCover config file for command line NUnit test coverage

So you want to produce a coverage report for your .Net project, preferably from the command line? If you use dotCover and NUnit then this:

<?xml version="1.0" encoding="utf-8"?>
<AnalyseParams>
    <Executable><!-- Path to your NUnit bin directory e.g.  -->C:\Program Files\NUnit 2.5.10\bin\net-2.0\nunit-console.exe</Executable>
    <WorkingDir><!-- This path works for running dotCover with a config file in the project directory-->bin\Debug\</WorkingDir>
    <Arguments><!-- The dlls containing NUnit tests. Space delimited if more than one-->My.Tests.dll My.MoreTests.dll</Arguments>
    <Output><!-- Path to where I want the report. Can be relative or absolute -->My.Tests.Coverage.html</Output>
    <Filters>
        <IncludeFilters>
            <FilterEntry><!--  _ "Module" means project _ --><ModuleMask>*</ModuleMask></FilterEntry>
        </IncludeFilters>
        <ExcludeFilters>
            <FilterEntry><!--  _ "Module" means project _ --><ModuleMask>My.Tests</ModuleMask></FilterEntry>
            <FilterEntry><!-- namespaces can be filter with a ClassMask with * wildcard --><ClassMask>Namespaces.For.AutogeneratedCode.*</ClassMask></FilterEntry>
            <FilterEntry><ClassMask>SomeUntestable.Class</ClassMask></FilterEntry>
        </ExcludeFilters>
    </Filters>
    <ReportType>html</ReportType>
 </AnalyseParams>

will allow you, from the command line, to type:

dotCover analyse MyConfigFileName.xml

and generate coverage reports. Assuming that dotCover is in your path of course.
I like to set the filters to exclude coverge report on the test project itself as well as autogenerated code.

Covering Multiple Test Projects In One Run

  • Set your working directory to be a parent of all the test projects, e.g. the solution directory.
  • List the full relative paths to each Test dll, space limited:
    <WorkingDir>.</WorkingDir>
    <Arguments>Web.Tests\bin\Debug\MyProject.Web.Tests.dll Implementation.Tests\bin\Debug\MyProject.Implementation.Tests.dll</Arguments>

Filtering and more advanced coverage configs

  • Look down the right hand side of the page here : http://www.jetbrains.com/dotcover/documentation/index.html for documentation, such as it is.
  • Filtering is covered here: http://blogs.jetbrains.com/dotnet/2010/07/filtering-with-dotcover/
  • More complex stuff is touched on here: http://blogs.jetbrains.com/dotnet/tag/code-coverage/

Use SqlExpress or Sql Server for Asp.Net Session

Problems using Sql Server or Sql Express for Asp.Net Session State

So you’ve run aspnet_regsql.exe -S .\SqlExpress -E -ssadd -sstype p or something like that, after following instructions about Asp.Net Session State Modes (in particular noting the instructions about the Agent XP setting for SqlExpress if you’re using SqlExpress) and you’ve set your web.config sessionState section; and you hoped that aspnet_regsql might do something useful like give permissions to your machine’s AspNet account to use the session state and it would all Just Work. Aaah. You can hope.

Error messages when setting up Asp.Net to use SqlServer Session State

Cannot open database requested in login ‘ASPState’. Login failed for user {MachineName}\ASPNET

Unable to use SQL Server because ASP.NET version 2.0 Session State is not installed on the SQL server. Please install ASP.NET Session State SQL Server version 2.0 or above

Failed to login to session state SQL server for user ‘AspNetSqlLogin’

Example Web.Config section

<sessionState
    cookieless="false"
    regenerateExpiredSessionId="true"
    mode="SQLServer"
    timeout="30"
    sqlConnectionString="Data Source=.\SqlExpress;Integrated Security=SSPI;"
    stateNetworkTimeout="30">

Solution: Give permissions on Sql Server to your AspNet account

Note the username from your error page telling you what account Asp.Net is using to login to your server. Then, in Sql Management Studio or somesuch:

  1. Create a login for that Windows user
  2. Add the login as a user to your AspState database
  3. Give permissions to that user in that database by making it a member of the owner role

I first tried making the AspNet account a member of the db_reader & db_writer roles, but that didn’t work; making it a database owner did work.

But I put SessionState on a Sql Server instance on a different machine

Then you’re hopefully running your servers within a domain and you can set Asp.Net to run under a domain account, and you can give permissions on Sql server to that domain account.
Or, you create a new Sql Server login. Similar to the above process, but instead of finding an existing Windows login in Sql Management Studio, you create a new Sql Server login). The you specify a connection string with a Sql Security instead of Integrated Security: sqlConnectionString="Data Source=.\SqlExpress;User Id=SqlLoginForAspNet;Password=XXXXXX;

But I get a

Failed to login to session state SQL server for user

and

Login failed for user ‘AspNetSqlLogin’. The user is not associated with a trusted SQL Server connection

That’s because your Sql Server has been configured for Windows Authentication Mode only. Configure it for both Windows and Sql Server Authentication Mode via the Database Properties – Security tab.
When the Gui tells you to restart Sql Server you can do so like this:
[dos]net stop “Sql Server (SQLExpress)”
net start “Sql Server (SQLExpress)”[/dos]
Or do it from Control Panel — Services.