internal/mod: init

internal/mod/root.go

@@ -0,0 +1,20 @@
+package mod
+
+import (
+	"os/exec"
+	"strings"
+)
+
+// Root contains the absolute path of the module root. Its value is empty if
+// used outside of a module.
+var Root string
+
+func init() {
+	stdout, _ := exec.Command("go", "env", "GOMOD").Output()
+
+	var ok bool
+	Root, ok = strings.CutSuffix(strings.TrimSpace(string(stdout)), "/go.mod")
+	if !ok {
+		Root = ""
+	}
+}

internal/mod/root_test.go

@@ -0,0 +1,14 @@
+package mod_test
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/lmittmann/w3/internal/mod"
+)
+
+func TestModRoot(t *testing.T) {
+	if !strings.HasSuffix(mod.Root, "w3") {
+		t.Fatalf("Unexpected module root: %q", mod.Root)
+	}
+}