% From Enrico Gregorio, testing stretch and shrink of the font.
% Public domain.
\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{inconsolata}
\parindent=0pt

\begin{document}
\ttfamily
Inconsolata

\settowidth{\dimen0}{123456789012345678901234567}

\vbox{\hsize=\dimen0
1234567890123456789012345\\
This should be monospaced\\
without spaces shrinking!\\
1 3 5 7 9 1 3 5 7 9 1 3 5 28
}

In the following only 30
characters should fit:

\settowidth{\dimen0}{A}

\leavevmode\hbox to30\dimen0{%
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8} (they are 35)

\hbox{%
123456789012345678901234567890}

% 
\bigskip \hrule \bigskip

\fontfamily{cmtt}\selectfont
Computer Modern Typewriter

\settowidth{\dimen0}{123456789012345678901234567}

\vbox{\hsize=\dimen0
1234567890123456789012345\\
This should be monospaced\\
without spaces shrinking!\\
1 3 5 7 9 1 3 5 7 9 1 3 5 28
}

In the following only 30
characters should fit:

\settowidth{\dimen0}{A}

\leavevmode\hbox to30\dimen0{%
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8} (they are 35)

\hbox{%
123456789012345678901234567890}

\end{document}