Adds handler for workspace with no path specified

cargo/lib/dependabot/cargo/file_fetcher.rb

@@ -359,7 +359,12 @@ def required_path?(file, path)
       def expand_workspaces(path)
         path = Pathname.new(path).cleanpath.to_path
         dir = directory.gsub(%r{(^/|/$)}, "")
-        unglobbed_path = T.must(path.split("*").first).gsub(%r{(?<=/)[^/]*$}, "")
+
+        unglobbed_path = if path.eql?("*")
+                           String(nil)
+                         else
+                           T.must(path.split("*").first).gsub(%r{(?<=/)[^/]*$}, "")
+                         end
 
         repo_contents(dir: unglobbed_path, raise_errors: false)
           .select { |file| file.type == "dir" }

cargo/spec/dependabot/cargo/file_fetcher_spec.rb

@@ -656,6 +656,25 @@
             .to eq(["file"])
         end
       end
+
+      context "with a glob that has a wild card '*' but no directory information specified" do
+        let(:parent_fixture) do
+          fixture(
+            "github",
+            "contents_cargo_manifest_workspace_with_no_path.json"
+          )
+        end
+
+        it "fetches the workspace dependency's Cargo.toml" do
+          expect(file_fetcher_instance.files.map(&:name))
+            .to match_array(
+              %w(Cargo.toml
+                 .cargo/config.toml)
+            )
+          expect(file_fetcher_instance.files.map(&:type).uniq)
+            .to eq(["file"])
+        end
+      end
     end
   end
 

cargo/spec/fixtures/github/contents_cargo_manifest_workspace_with_no_path.json

@@ -0,0 +1,18 @@
+{
+  "name": "Cargo.toml",
+  "path": "Cargo.toml",
+  "sha": "cb9ddc34d2c13ca51bd54ec7374d89cbad814d78",
+  "size": 213,
+  "url": "https://api.github.com/repos/runconduit/conduit/contents/Cargo.toml?ref=master",
+  "html_url": "https://github.com/runconduit/conduit/blob/master/Cargo.toml",
+  "git_url": "https://api.github.com/repos/runconduit/conduit/git/blobs/cb9ddc34d2c13ca51bd54ec7374d89cbad814d78",
+  "download_url": "https://raw.githubusercontent.com/runconduit/conduit/master/Cargo.toml",
+  "type": "file",
+  "content": "W3dvcmtzcGFjZV0KbWVtYmVycyA9IFsiLi8qL3N1Yl8qIl0=\n",
+  "encoding": "base64",
+  "_links": {
+    "self": "https://api.github.com/repos/runconduit/conduit/contents/Cargo.toml?ref=master",
+    "git": "https://api.github.com/repos/runconduit/conduit/git/blobs/cb9ddc34d2c13ca51bd54ec7374d89cbad814d78",
+    "html": "https://github.com/runconduit/conduit/blob/master/Cargo.toml"
+  }
+}