assets builder tools (#39)

Reviewed-on: #39
Reviewed-by: xtul <mpiasecki720@protonmail.com>

internal/assets/helpers_test.go

@@ -0,0 +1,63 @@
+package assets
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestWalk(t *testing.T) {
+	root := t.TempDir()
+	must := func(rel string) {
+		p := filepath.Join(root, rel)
+		if err := os.MkdirAll(filepath.Dir(p), 0o755); err != nil {
+			t.Fatal(err)
+		}
+		if err := os.WriteFile(p, []byte("x"), 0o644); err != nil {
+			t.Fatal(err)
+		}
+	}
+	must("a.MDL")
+	must("sub/b.mdl")
+	must("sub/c.txt")
+
+	exts := map[string]bool{".mdl": true}
+	got, err := walk([]string{root}, exts, true)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(got) != 2 {
+		t.Fatalf("recursive walk = %v, want 2 mdl files", got)
+	}
+
+	got, _ = walk([]string{root}, exts, false)
+	if len(got) != 1 || filepath.Base(got[0]) != "a.MDL" {
+		t.Fatalf("non-recursive walk = %v, want only a.MDL", got)
+	}
+
+	// A file argument that matches is included directly.
+	got, _ = walk([]string{filepath.Join(root, "sub", "b.mdl")}, exts, true)
+	if len(got) != 1 {
+		t.Fatalf("file arg walk = %v, want the file itself", got)
+	}
+}
+
+func TestLook(t *testing.T) {
+	dir := t.TempDir()
+	stub := filepath.Join(dir, "mytool")
+	if err := os.WriteFile(stub, []byte("#!/bin/sh\n"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	t.Setenv("PATH", dir)
+
+	if got := look("nope-not-here", "mytool"); got == "" {
+		t.Fatal("look should find mytool on PATH")
+	}
+	// Explicit existing path candidate.
+	if got := look(stub); got != stub {
+		t.Fatalf("look(%q) = %q, want the path itself", stub, got)
+	}
+	if got := look("definitely-absent-binary-xyz"); got != "" {
+		t.Fatalf("look = %q, want empty", got)
+	}
+}