Code Contracts: ensure constraint on delegate to avoid "requires unproven" warning?

Code Contracts: ensure constraint on delegate to avoid "requires unproven" warning?

By : user2955542
Date : November 22 2020, 10:40 AM
Hope that helps f is not known to be pure. Calling it twice may give different results, so assuming that the first result is non-null says nothing about the second result.
You should be able to store the result in a variable, add an assumption about that variable, and then pass that to your other method.
code :
if (!s.HasValue)
    var val = f(s.Object);
    Contract.Assume(val != null);

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Why I still get Code Contracts : Ensure unproven warning?

Why I still get Code Contracts : Ensure unproven warning?

By : user2469235
Date : March 29 2020, 07:55 AM
Does that help This is a limitation of the implementation of Contracts in the mscorlib dll.
See this link on the official Code Contracts forum.
code :
[Pure, Reads(ReadsAttribute.Reads.Nothing)]
public static string Format(string format, object[] args)
    string str;
    Contract.Requires((bool) (format != null), null, "format != null");
    Contract.Requires((bool) (args != null), null, "args != null");
    Contract.Ensures((bool) (Contract.Result<string>() != null), null, "Contract.Result<String>() != null");
    return str;
.NET 4 Code Contracts: "requires unproven: source != null"

.NET 4 Code Contracts: "requires unproven: source != null"

By : biji
Date : March 29 2020, 07:55 AM
I wish this helpful for you My guess is that one of the methods CreateSet, OfType and AsEnumerable is declared as an extension method with a this-parameter called "source", and CodeContrcts can't prove it is not null. Also, don't you need to add a Requires clause to specify that _uow is non-null on entry?
CreateSet appears to be the extension method since it doesn't appear in MSDN. If the method should never return null, you can enforce this by adding this contract to CreateSet:
code :
Contract.Ensures(Contract.Result<T>() != null);
Code Contracts: how to suppress this "requires unproven" warning?

Code Contracts: how to suppress this "requires unproven" warning?

By : user3748478
Date : March 29 2020, 07:55 AM
wish of those help Try Contract.Ensures(Contract.Result() == !string.IsNullOrWhitespace(s))
code :
public static bool IsEmpty(this string s) 
    Contract.Ensures(Contract.Result() == string.IsNullOrWhitespace(s))
    return string.IsNullOrWhitespace(s);

public static bool IsNotEmpty(this string s) 
    Contract.Ensures(Contract.Result() == !string.IsNullOrWhitespace(s))
    return !string.IsNullOrWhitespace(s);
Code Contracts warn of "ensures unproven" when locks are involved

Code Contracts warn of "ensures unproven" when locks are involved

By : Stuart Pineo
Date : March 29 2020, 07:55 AM
will be helpful for those in need Here's how the static checker treats locks and invariants:
If you lock something with the form lock(x.foo) { ... }, the static checker considers x.foo as the protecting lock of x. At the end of the lock scope, it assume that other threads might access x and modify it. As a result, the static checker assumes that all fields of x only satisfy the object invariant after the lock scope, nothing more.
Code Contracts: Ensures Unproven & Requires Unproven

Code Contracts: Ensures Unproven & Requires Unproven

By : Murat Celik
Date : March 29 2020, 07:55 AM
may help you . "I have a custom Dictionary wrapper class" - that implements IDictionary. Interface methods can specify contracts, and the class methods that implement them must meet the contracts. In this case, IDictionary.ContainsKey(TKey) has the contract you're asking about:
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