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.

1 files changed, 101 insertions, 0 deletions

diff --git a/tests/test_functions/mktemp.fish b/tests/test_functions/mktemp.fish
new file mode 100644
index 00000000..78549f3b
--- /dev/null
+++ b/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