Unit testing a function returning void

[Ali Çehreli]

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