The issue was that average always threw an exception.
Here is the "final" working code, which passes the unit tests.
source/app.d
```
import std.stdio : writeln;
import std.exception : assertThrown, assertNotThrown;
void main()
{
}
class UnequalLengths : Exception
{
this(string msg, string file = __FILE__, size_t line = __LINE__)
{
super(msg, file, line);
writeln("Unequal lengths");
}
}
class RangeError : Exception
{
this(string msg, string file = __FILE__, size_t line = __LINE__)
{
super(msg, file, line);
writeln("Range error");
}
}
int[] average(int[] a, int[] b)
{
if (a.length != b.length)
{
throw new UnequalLengths("Unequal lengths");
}
int[] result;
result.length = a.length;
result[] = (a[] + b[]) / 2;
return result;
}
unittest
{
// Must throw UnequalLengths for uneven slices
assertThrown!UnequalLengths(average([1], [1, 2]));
/* The equivalent of the line above */
/+
{
auto isUnequalLengthsThrown = false;
try
{
average([1], [1, 2]);
}
catch (UnequalLengths exc)
{
isUnequalLengthsThrown = true;
}
assert(isUnequalLengthsThrown == true);
}
+/
// Must not throw RangeError for empty slices (it may throw
other types of exceptions)
assertNotThrown!RangeError(average([], []));
/* The equivalent of the line above */
/+
{
auto inRangeErrorThrown = false;
try
{
average([1], [1, 2]);
}
catch (RangeError exc)
{
inRangeErrorThrown = true;
}
catch (Exception exc)
{
// do nothing
}
assert(inRangeErrorThrown == false);
}
+/
}
```
