\begin{figure*}[tb]
    \centering
<<fig=TRUE,height=3.5>>=
    tests <- reports
    tests <- tests[is.finite(tests$tests.run),]
    tests$tests.total.errors <- tests$tests.failures + tests$tests.errors
    tests$display_order <- unlist(by(tests, tests$project, function(x) order(order(x$timestamp))))
    tests <- melt(tests, id.vars=c('project', 'bug_number', 'bug_id', 'display_order'), measure.vars=c('tests.run', 'tests.total.errors', 'coverage.overall'))
    tests <- tests[!is.na(tests$value),]
    tests$project <- format_name(tests$project)
    tests$variable <- format_name(tests$variable)
    fig <- ggplot(tests, aes(display_order, value)) +
        geom_point(shape='.') +
        facet_grid(variable ~ project, scales='free') +
        labs(x='Bugs ordered by report date') +
        theme(text=element_text(size=7.5),
              axis.text=element_text(colour='black'),
              axis.text.x=element_text(angle=90),
              axis.title.y=element_blank(),
              panel.border=element_rect(colour='black', fill=NA)
        )
    print(fig)
@

    \caption{Tests run and coverage levels}
    \label{fig:tests_over_time}
\end{figure*}
