Add a test for --help

xtests/help

@@ -0,0 +1,44 @@
+Usage:
+  exa [options] [files...]
+
+  -?, --help         show list of command-line options
+  -v, --version      show version of exa
+
+DISPLAY OPTIONS
+  -1, --oneline      display one entry per line
+  -l, --long         display extended file metadata as a table
+  -G, --grid         display entries as a grid (default)
+  -x, --across       sort the grid across, rather than downwards
+  -R, --recurse      recurse into directories
+  -T, --tree         recurse into directories as a tree
+  -F, --classify     display type indicator by file names
+  --colo[u]r=WHEN    when to use terminal colours (always, auto, never)
+  --colo[u]r-scale   highlight levels of file sizes distinctly
+
+FILTERING AND SORTING OPTIONS
+  -a, --all                  don't hide hidden and 'dot' files
+  -d, --list-dirs            list directories like regular files
+  -r, --reverse              reverse the sort order
+  -s, --sort SORT_FIELD      which field to sort by:
+  --group-directories-first  list directories before other files
+  -I, --ignore-glob GLOBS    glob patterns (pipe-separated) of files to ignore
+  Valid sort fields:         name, Name, extension, Extension, size,
+                             modified, accessed, created, inode, none
+
+
+LONG VIEW OPTIONS
+  -b, --binary       list file sizes with binary prefixes
+  -B, --bytes        list file sizes in bytes, without any prefixes
+  -g, --group        list each file's group
+  -h, --header       add a header row to each column
+  -H, --links        list each file's number of hard links
+  -i, --inode        list each file's inode number
+  -L, --level DEPTH  limit the depth of recursion
+  -m, --modified     use the modified timestamp field
+  -S, --blocks       show number of file system blocks
+  -t, --time FIELD   which timestamp field to list (modified, accessed, created)
+  -u, --accessed     use the accessed timestamp field
+  -U, --created      use the created timestamp field
+  --git              list each file's Git status, if tracked
+  -@, --extended     list each file's extended attributes and sizes
+

xtests/run.sh

@@ -109,5 +109,7 @@ $exa $testcases/links/* -1 | diff -q - $results/links_1_files || exit 1
 $exa $testcases/git/additions -l --git 2>&1 | diff -q - $results/git_additions  || exit 1
 $exa $testcases/git/edits     -l --git 2>&1 | diff -q - $results/git_edits      || exit 1
 
+# And finally...
+$exa --help 2>&1 | diff -q - $results/help || exit 1
 
 echo "All the tests passed!"