Re: Unit testing a function returning void

[Ali Çehreli via Digitalmars-d-learn]

On 11/3/22 03:00, Bruno Pagis wrote:

>    void print() {
>      writeln("array = ", this.array);
>    }
Similar to Paul Backus's program but I would try to avoid the file 
system for unit tests when possible. In this case, you can print into a 
sink, which can be useful in other ways as well:

import std.stdio;

class A
{
    int[] a;

    this(int[] a) { this.a = a; }

    void toString(scope void delegate(in char[]) sink) const {
        import std.conv : text;
        sink("array = ");
        sink(this.a.text); // or this.a.to!string

        // The following alternative may be a little heavier weight:
        // import std.format : formattedWrite;
        // sink.formattedWrite!"array = %s"(this.a);
    }

    void print() {
        writeln(this);
    }
}

unittest {
    import std.file;

    A a = new A([1, 2]);

    import std.conv : text;
    assert(a.text == "array = [1, 2]");
}

void main() {}

toString is the textual representation of the object. If you don't want 
the same output for that purpose, you can use a different name from 
toString but you have to use an explicit "sink" but I really think the 
above is what you want. :)

Ali