Define a common mktemp for tests

GNU and BSD `mktemp` handle options differently, and it's a useful
utility for tests. As such, define a common `mktemp` function wrapper
for the test suite.

It might actually be nice to expand this for more flags and support it
globally, but that may result in confusion for any users of BSD mktemp
that expect to be running /bin/mktemp.

tests/expansion.in

@@ -82,11 +82,10 @@ echo ()[1]
 echo ()[d]
 
 # Test tilde expansion
-# On OS X, we must pass an argument to mktemp,
-# and /tmp is symlinked to /private/tmp
+# On OS X, /tmp is symlinked to /private/tmp
 # $PWD is our best bet for resolving it
 set -l saved $PWD
-cd (mktemp -d /tmp/fish_tilde_XXXXXX)
+cd (mktemp -d)
 set tmpdir $PWD
 cd $saved
 mkdir $tmpdir/realhome

tests/test_functions/mktemp.fish

@@ -0,0 +1,101 @@
+# GNU and BSD mktemp differ in their handling of arguments
+# Let's expose a simplified common interface
+function mktemp
+    # usage: mktemp [-d] [-t] [template]
+    #
+    # If the -d flag is given, create a directory.
+    #
+    # If the -t flag is given, treat the template as a filename relative
+    # to the temporary directory. The template may contain slashes but only
+    # the final path component is created by mktemp. The template must not be
+    # absolute
+    #
+    # If no template is given, assume tmp.XXXXXXXXXX and -t.
+    set -l opts
+    while set -q argv[1]
+        switch $argv[1]
+        case -d
+            set opts $opts d
+        case -t
+            set opts $opts t
+        case --
+            set -e argv[1]
+            break
+        case '-*'
+            echo "mktemp: unknown flag $argv[1]" >&2
+            _mktemp_help >&2
+            exit 2
+        case '*'
+            break
+        end
+        set -e argv[1]
+    end
+
+    set -l template
+    if set -q argv[1]
+        set template $argv[1]
+    else
+        set template 'tmp.XXXXXXXXXX'
+        set opts $opts t
+    end
+
+    if set -q argv[2]
+        echo 'mktemp: too many templates' >&2
+        _mktemp_help >&2
+        exit 1
+    end
+
+    # GNU sed treats the final occurrence of a sequence of X's as the template token.
+    # BSD sed only treats X's as the template token if they suffix the string.
+    # So let's outlaw them anywhere besides the end.
+    # Similarly GNU sed requires at least 3 X's, BSD sed requires none. Let's require 3.
+    begin
+        set -l IFS
+        printf '%s' "$template" | read -la chars
+        set -l found_x
+        for c in $chars
+            if test $c = X
+                set found_x $found_x X
+            else if set -q found_x[1]
+                echo 'mktemp: X\'s may only occur at the end of the template' >&2
+                _mktemp_help >&2
+                exit 1
+            end
+        end
+        if test (count $found_x) -lt 3
+            echo "mktemp: too few X's in template '$template'" >&2
+            _mktemp_usage >&2
+            exit 1
+        end
+    end
+
+    set -l args
+    if contains d $opts
+        set args $args -d
+    end
+    if contains t $opts
+        switch $template
+        case '/*'
+            echo "mktemp: invalid template '$template' with -t, template must not be absolute" >&2
+            _mktemp_help >&2
+            exit 1
+        end
+
+        switch "$TMPDIR"
+        case ''
+            set template /tmp/$template
+        case '*/'
+            set template $TMPDIR$template
+        case '*'
+            set template $TMPDIR/$template
+        end
+    end
+    set args $args $template
+
+    command mktemp $args
+end
+
+function _mktemp_help
+    echo 'usage: mktemp [-d] [-t] [template]'
+    echo 'note: mktemp is a test function, see tests/test_functions/mktemp.fish'
+end

tests/test_util.fish

@@ -1,3 +1,4 @@
+# vim: set ts=4 sw=4 et:
 # Utilities for the test runners
 
 if test "$argv[1]" = (status -f)
@@ -38,8 +39,10 @@ if not set -q __fish_is_running_tests
         rm -r $XDG_CONFIG_HOME; or die
     end
     mkdir -p $XDG_CONFIG_HOME/fish; or die
+    ln -s $PWD/test_functions $XDG_CONFIG_HOME/fish/functions; or die
     set -l escaped_parent (dirname $PWD | sed -e 's/[\'\\\\]/\\\\&/g'); or die
-    printf 'set fish_function_path \'%s/share/functions\'\n' $escaped_parent > $XDG_CONFIG_HOME/fish/config.fish; or die
+    set -l escaped_config (printf '%s/fish' $XDG_CONFIG_HOME | sed -e 's/[\'\\\\]/\\\\&/g'); or die
+    printf 'set fish_function_path \'%s/functions\' \'%s/share/functions\'\n' $escaped_config $escaped_parent > $XDG_CONFIG_HOME/fish/config.fish; or die
     set -xl __fish_is_running_tests $XDG_CONFIG_HOME
     exec ../fish $script
     die 'exec failed'
@@ -51,10 +54,12 @@ else if test "$__fish_is_running_tests" != "$XDG_CONFIG_HOME"
 else
     # we're running tests with a temporary config directory
     function test_util_on_exit --on-process-exit %self -V __fish_is_running_tests
-        # remove the temporary config directory
-        # unfortunately if this fails we can't alter the exit status of fish
-        if not rm -r "$__fish_is_running_tests"
-            echo "error: Couldn't remove temporary config directory '$__fish_is_running_tests'" >&2
+        if not set -q __fish_test_keep_tmp_config
+            # remove the temporary config directory
+            # unfortunately if this fails we can't alter the exit status of fish
+            if not rm -r "$__fish_is_running_tests"
+                echo "error: Couldn't remove temporary config directory '$__fish_is_running_tests'" >&2
+            end
         end
     end
     # unset __fish_is_running_tests so any children that source