fix edge case in output path generation

Cargo.lock

@@ -1332,7 +1332,7 @@ checksum = "a3f87b73ce11b1619a3c6332f45341e0047173771e8b8b73f87bfeefb7b56244"
 
 [[package]]
 name = "registry-backup"
-version = "0.4.0-rc.3"
+version = "0.4.0-rc.4"
 dependencies = [
  "chrono",
  "clap",

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "registry-backup"
 authors = ["Jonathan Strong <jstrong@shipyard.rs>"]
-version = "0.4.0-rc.3"
+version = "0.4.0-rc.4"
 edition = "2021"
 publish = ["shipyard-rs-public"]
 readme = "README.md"

config.toml.sample

@@ -15,3 +15,4 @@ max-concurrent-requests = 50
 [output]
 path = "output"
 overwrite-existing = false
+format = "{crate}/{version}/download"

src/main.rs

@@ -86,12 +86,14 @@ impl RegistryConfig {
             out = out.replace("{sha256-checksum}", cksum);
             out
         } else {
-            format!(
+            Path::new(&self.dl)
-                "{dl}/{name}/{version}/download",
+                .join(&format!(
-                dl = self.dl,
+                    "{name}/{version}/download",
                     name = name,
                     version = version,
-            )
+                ))
+                .display()
+                .to_string()
         }
     }
 }
@@ -808,4 +810,25 @@ mod tests {
 
         assert_eq!(output_path, Path::new("output/lazy-static/x7b2z899"),);
     }
+
+    #[test]
+    fn verify_blank_url_template_works_same_as_default() {
+        let c1 = RegistryConfig {
+            dl: "{crate}/{version}/download".to_string(),
+            api: String::new(),
+            allowed_registries: vec![],
+            auth_required: Some(true),
+        };
+        let mut c2 = c1.clone();
+        c2.dl = "".to_string();
+
+        assert_eq!(
+            c1.get_dl_url("lazy-static", "1.0.0", "x7b2z899"),
+            c2.get_dl_url("lazy-static", "1.0.0", "x7b2z899"),
+        );
+        assert_eq!(
+            Path::new("output").join(c1.get_dl_url("lazy-static", "1.0.0", "x7b2z899")),
+            Path::new("output/lazy-static/1.0.0/download"),
+        );
+    }
 }