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Programming in D: The Ultimate Guide for Software Engineers

Solution: Make the Unit Test Pass

This lesson provides a solution to the challenge given in the previous lesson.

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Solution

For demonstration purposes, let’s write an obviously incorrect implementation that passes the first test by accident. The following function simply returns a copy of the input:

D
dstring toFront(dstring str, dchar letter) {
    dstring result;
    foreach (c; str) {
        result ~= c;
    }
    return result;
}
unittest {
    immutable str = "hello"d;
    assert(toFront(str, 'h') == "hello");
    assert(toFront(str, 'o') == "ohell");
    assert(toFront(str, 'l') == "llheo");
}
void main() {
}

Here is a correct ...