genautocomplete: add support for fish shell

cmd/genautocomplete/genautocomplete_fish.go

@@ -0,0 +1,44 @@
+package genautocomplete
+
+import (
+	"log"
+
+	"github.com/rclone/rclone/cmd"
+	"github.com/spf13/cobra"
+)
+
+func init() {
+	completionDefinition.AddCommand(fishCommandDefinition)
+}
+
+var fishCommandDefinition = &cobra.Command{
+	Use:   "fish [output_file]",
+	Short: `Output fish completion script for rclone.`,
+	Long: `
+Generates a fish autocompletion script for rclone.
+
+This writes to /etc/fish/completions/rclone.fish by default so will
+probably need to be run with sudo or as root, eg
+
+    sudo rclone genautocomplete fish
+
+Logout and login again to use the autocompletion scripts, or source
+them directly
+
+    . /etc/fish/completions/rclone.fish
+
+If you supply a command line argument the script will be written
+there.
+`,
+	Run: func(command *cobra.Command, args []string) {
+		cmd.CheckArgs(0, 1, command, args)
+		out := "/etc/fish/completions/rclone.fish"
+		if len(args) > 0 {
+			out = args[0]
+		}
+		err := cmd.Root.GenFishCompletionFile(out, true)
+		if err != nil {
+			log.Fatal(err)
+		}
+	},
+}

cmd/genautocomplete/genautocomplete_test.go

@@ -33,3 +33,16 @@ func TestCompletionZsh(t *testing.T) {
 	assert.NoError(t, err)
 	assert.NotEmpty(t, string(bs))
 }
+
+func TestCompletionFish(t *testing.T) {
+	tempFile, err := ioutil.TempFile("", "completion_fish")
+	assert.NoError(t, err)
+	defer func() { _ = tempFile.Close() }()
+	defer func() { _ = os.Remove(tempFile.Name()) }()
+
+	fishCommandDefinition.Run(fishCommandDefinition, []string{tempFile.Name()})
+
+	bs, err := ioutil.ReadFile(tempFile.Name())
+	assert.NoError(t, err)
+	assert.NotEmpty(t, string(bs))
+}