cfr-lm & sans serif small caps

Question

How can I have the sans serif small caps with this fonts?

\documentclass{book}

% Latin Modern with oldstyle digits    
\usepackage[% 
  rm={oldstyle,proportional},% 
  sf={oldstyle,proportional},% 
  tt={oldstyle=false,proportional=false,monowidth}% 
]{cfr-lm} 

\begin{document}
\sffamily\scshape test
\end{document}

Answer 1

There is no small caps shape in the Latin Modern Sans typeface family (either in Type1 or in OpenType format).

So the answer is "no, you can't have sans serif small caps", because the shape doesn't exist.

See this paper by W. Robertson for a description of the available faces and shapes.

Answer 2

For those who say it is impossible, is say watch this:

I found the sansmathfonts package (sansmathfonts documentation - CTAN), which in there documentation addresses this exact problem.

From their documentation:

The Computer Modern font family has a sans serif typeface. However, compared to the serif typeface, it is incomplete: there are no sans serif small caps or math fonts. Furthermore, the bold slanted font is not available as an outline font. This leads to highly unsatisfactory typography of documents that use sans serif for the body text. The sansmathfonts package provides these “missing” fonts.

So to get a "complete" sans-serif font, just add these two lines in the preable:

% Set sans-serif font (with small caps option and math option)
\usepackage{sansmathfonts}
% Apply font throughout the whole document    
\renewcommand{\familydefault}{cmsmf}

Anyhow, please make sure to comment out any other font packages, like for example

%\usepackage[T1]{fontenc}
%\usepackage{microtype}
%\usepackage{lmodern}

Note: This font also changes the math style to sans-serif. If you don't want that, I found that it works to add

\usepackage{lmodern}

after, the sansmathfonts package. (But I think a fitting math font is prettier.)

If you want any other fonts check out The Latex Font Catalogue