complete RESITC_HOST environment handling & test

changelog/unreleased/issue-4733

@@ -7,3 +7,4 @@ environment variable `RESTIC_HOST`. `--host` still takes precedence over the
 environment variable.
 
 https://github.com/restic/restic/issues/4733
+https://github.com/restic/restic/pull/4734

cmd/restic/find.go

@@ -19,13 +19,11 @@ func initMultiSnapshotFilter(flags *pflag.FlagSet, filt *restic.SnapshotFilter,
 	flags.Var(&filt.Tags, "tag", "only consider snapshots including `tag[,tag,...]` (can be specified multiple times)")
 	flags.StringArrayVar(&filt.Paths, "path", nil, "only consider snapshots including this (absolute) `path` (can be specified multiple times)")
 
-	if len(filt.Hosts) == 0 {
+	// set default based on env if set
-		// parse host from env, if not exists or empty the default value will be used
 	if host := os.Getenv("RESTIC_HOST"); host != "" {
 		filt.Hosts = []string{host}
 	}
 }
-}
 
 // initSingleSnapshotFilter is used for commands that work on a single snapshot
 // MUST be combined with restic.FindFilteredSnapshot
@@ -34,13 +32,11 @@ func initSingleSnapshotFilter(flags *pflag.FlagSet, filt *restic.SnapshotFilter)
 	flags.Var(&filt.Tags, "tag", "only consider snapshots including `tag[,tag,...]`, when snapshot ID \"latest\" is given (can be specified multiple times)")
 	flags.StringArrayVar(&filt.Paths, "path", nil, "only consider snapshots including this (absolute) `path`, when snapshot ID \"latest\" is given (can be specified multiple times)")
 
-	if len(filt.Hosts) == 0 {
+	// set default based on env if set
-		// parse host from env, if not exists or empty the default value will be used
 	if host := os.Getenv("RESTIC_HOST"); host != "" {
 		filt.Hosts = []string{host}
 	}
 }
-}
 
 // FindFilteredSnapshots yields Snapshots, either given explicitly by `snapshotIDs` or filtered from the list of all snapshots.
 func FindFilteredSnapshots(ctx context.Context, be restic.Lister, loader restic.LoaderUnpacked, f *restic.SnapshotFilter, snapshotIDs []string) <-chan *restic.Snapshot {

cmd/restic/find_test.go

@@ -0,0 +1,61 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/restic/restic/internal/restic"
+	rtest "github.com/restic/restic/internal/test"
+	"github.com/spf13/pflag"
+)
+
+func TestSnapshotFilter(t *testing.T) {
+	for _, test := range []struct {
+		name     string
+		args     []string
+		expected []string
+		env      string
+	}{
+		{
+			"no value",
+			[]string{},
+			nil,
+			"",
+		},
+		{
+			"args only",
+			[]string{"--host", "abc"},
+			[]string{"abc"},
+			"",
+		},
+		{
+			"env default",
+			[]string{},
+			[]string{"def"},
+			"def",
+		},
+		{
+			"both",
+			[]string{"--host", "abc"},
+			[]string{"abc"},
+			"def",
+		},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			t.Setenv("RESTIC_HOST", test.env)
+
+			for _, mode := range []bool{false, true} {
+				set := pflag.NewFlagSet("test", pflag.PanicOnError)
+				flt := &restic.SnapshotFilter{}
+				if mode {
+					initMultiSnapshotFilter(set, flt, false)
+				} else {
+					initSingleSnapshotFilter(set, flt)
+				}
+				err := set.Parse(test.args)
+				rtest.OK(t, err)
+
+				rtest.Equals(t, test.expected, flt.Hosts, "unexpected hosts")
+			}
+		})
+	}
+}