CODEWITHSUNDEEP
c#stringunit-testing
DisplayMyName
DisplayMyName

Reputation: 320

Unit Testing a method with a large string

I'm currently using C#, but I believe the question applies to more languages.

I have a method, which takes a string value, and throws an exception, if it's too big. I want to unit test it that the exception is correct.

int vlen = Encoding.UTF8.GetByteCount(value);
if (vlen < 0 || 0x0FFFFFFF < vlen)
   throw new ArgumentException("Valid UTF8 encodded value length is up to 256MB!", "value");

What is the best way to generate such a string? Should I just have a file of that size? Should I create such a file every time running unit tests?

Upvotes: 2

Views: 3514

Answers (3)

D Stanley
D Stanley

Reputation: 152566

string has a constructor that lest you specify a length and a characer to repeat:

string longString = new string('a',0x0FFFFFFF + 1);

Upvotes: 6

Ren&#233; Vogt
Ren&#233; Vogt

Reputation: 43896

You can simply use a StringBuilder:

StringBuilder builder = new StringBuilder();
builder.Append('a', 0x10000000);
string s = builder.ToString();

//Console.WriteLine(s.Length);

YourMethodToTest(s);

This takes no measurable time at my machine and I'm sure there won't be a serious performance issue on your machine either.

Upvotes: 1

Jamie Rees
Jamie Rees

Reputation: 8183

What I would usually use in Unit Tests is a package called AutoFixture.

With that you can do the following to generate a large string:

string.Join(string.Empty, Fixture.CreateMany<char>(length))

Upvotes: 0

Related Questions