diff --git a/cmd/restree/helpers_test.go b/cmd/restree/helpers_test.go
new file mode 100644
index 0000000..2c2c4b5
--- /dev/null
+++ b/cmd/restree/helpers_test.go
@@ -0,0 +1,29 @@
+package main
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestFilterSnapshots(t *testing.T) {
+	snapshots := []snapshot{
+		{ID: "alpha", Hostname: "laptop", Tags: []string{"daily"}},
+		{ID: "beta", Tags: []string{"weekly"}},
+		{ID: "gamma", Hostname: "server"},
+	}
+
+	if got, want := filterSnapshots(snapshots, "laptop", allTagsLabel), snapshots[:1]; !reflect.DeepEqual(got, want) {
+		t.Fatalf("host filter = %#v, want %#v", got, want)
+	}
+	if got, want := filterSnapshots(snapshots, allHostsLabel, noTagLabel), snapshots[2:]; !reflect.DeepEqual(got, want) {
+		t.Fatalf("no-tag filter = %#v, want %#v", got, want)
+	}
+}
+
+func TestTrimNestedPaths(t *testing.T) {
+	paths := []string{"/photos/2025", "/documents", "/photos", "/documents/work", "/music"}
+	want := []string{"/music", "/photos", "/documents"}
+	if got := trimNestedPaths(paths); !reflect.DeepEqual(got, want) {
+		t.Fatalf("trimNestedPaths() = %#v, want %#v", got, want)
+	}
+}
diff --git a/cmd/restree/restic_test.go b/cmd/restree/restic_test.go
new file mode 100644
index 0000000..165acf8
--- /dev/null
+++ b/cmd/restree/restic_test.go
@@ -0,0 +1,33 @@
+package main
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestParseLSEntries(t *testing.T) {
+	out := []byte("{\"name\":\"documents\",\"path\":\"/documents\",\"type\":\"dir\"}\n{\"name\":\"notes.txt\",\"path\":\"/documents/notes.txt\",\"type\":\"file\",\"size\":42}\n")
+	want := []lsEntry{
+		{Name: "documents", Path: "/documents", Type: "dir"},
+		{Name: "notes.txt", Path: "/documents/notes.txt", Type: "file", Size: 42},
+	}
+	got, err := parseLSEntries(out)
+	if err != nil || !reflect.DeepEqual(got, want) {
+		t.Fatalf("parseLSEntries() = %#v, %v; want %#v, nil", got, err, want)
+	}
+	if _, err := parseLSEntries([]byte("not json")); err == nil {
+		t.Fatal("expected malformed ls output to fail")
+	}
+}
+
+func TestParseFindEntries(t *testing.T) {
+	out := []byte("[{\"matches\":[{\"path\":\"/documents/a.txt\",\"type\":\"file\"}]},{\"matches\":[{\"path\":\"/photos\",\"type\":\"dir\"}]}]")
+	want := []lsEntry{
+		{Path: "/documents/a.txt", Type: "file"},
+		{Path: "/photos", Type: "dir"},
+	}
+	got, err := parseFindEntries(out)
+	if err != nil || !reflect.DeepEqual(got, want) {
+		t.Fatalf("parseFindEntries() = %#v, %v; want %#v, nil", got, err, want)
+	}
+}
diff --git a/justfile b/justfile
index 23fc290..fb6c094 100644
--- a/justfile
+++ b/justfile
@@ -115,11 +115,21 @@ run:
     just build
     "{{bin}}/{{app}}-{{version}}-$(go env GOOS)-$(go env GOARCH)"
 
+check:
+    just lint
+    just test
+
 lint:
     goimports -w {{pkg}}
     go vet ./{{pkg}}
     staticcheck ./{{pkg}}
 
+test:
+    go test ./...
+
+test-race:
+    go test -race ./...
+
 bump new:
     #!/usr/bin/env bash
     set -euo pipefail