Report duration of tests

OSX `date` does not support milliseconds output, so @derekstavis created
this `C` code to generate the time with milliseconds.

pkg/fish-spec/basic_formatter.fish

+function __fish-spec.all_specs_init -e all_specs_init -a spec
+  set -g __fish_spec_start_time (__fish-spec.current_time)
+end
+
+function __fish-spec.all_specs_finished -e all_specs_finished -a spec
+  set -l __fish_spec_end_time (__fish-spec.current_time)
+  set -l diff (math "scale=3;($__fish_spec_end_time - $__fish_spec_start_time) / 1000")
+
+  echo -en '\n\nFinished in '
+  printf '%g' $diff
+  echo ' seconds'
+end
+
 function __fish-spec.spec_init -e spec_init -a spec
   set -g __current_spec_name (echo $spec | sed 's/^[0-9]*_//;s/_/ /g;s/^it/It/')
   set -e __current_spec_output

pkg/fish-spec/functions/fish-spec.fish

 function fish-spec
+  set -g __fish_spec_dir (dirname (dirname (status -f)))
+
   # Source formatter
-  set -l fish_spec_dir (dirname (dirname (status -f)))
-  source $fish_spec_dir/basic_formatter.fish
+  source $__fish_spec_dir/basic_formatter.fish
 
   # Reset internal variables
   set -e __any_spec_failed
@@ -14,9 +15,13 @@ function fish-spec
   # Load helper file
   source spec/helper.fish ^/dev/null
 
+  emit all_specs_init
+
   # Run all specs
   __fish-spec.run_all_specs
 
+  emit all_specs_finished
+
   not set -q __any_spec_failed
 end
 
@@ -50,3 +55,13 @@ function __fish-spec.run_suite -a suite_name
 
   functions -e before_all before_each after_each after_all
 end
+
+function __fish-spec.current_time
+  if test (uname) = 'Darwin'
+    set filename 'epoch.osx'
+  else
+    set filename 'epoch.linux'
+  end
+
+  eval $__fish_spec_dir/utils/$filename
+end

pkg/fish-spec/utils/epoch.c

+#include <stdio.h>
+#include <sys/time.h>
+
+int main(int argc, char** argv) {
+  struct timeval time_struct;
+  gettimeofday(&time_struct, 0);
+  printf("%lld", (time_struct.tv_sec * 1000ll) + (time_struct.tv_usec / 1000ll));
+
+  return 0;
+}