Add extra test cases

spec/ameba/glob_utils_spec.cr

@@ -51,6 +51,24 @@ module Ameba
           subject.expand(["foo/*"])
         end
       end
+
+      it "raises an ArgumentError when given a missing file" do
+        expect_raises(ArgumentError, "No files found matching foo.cr") do
+          subject.expand(["foo.cr"])
+        end
+      end
+
+      it "raises an ArgumentError when given a missing directory" do
+        expect_raises(ArgumentError, "No files found matching foo/") do
+          subject.expand(["foo/"])
+        end
+      end
+
+      it "raises an ArgumentError when given multiple arguments, one of which is missing" do
+        expect_raises(ArgumentError, "No files found matching foo.cr") do
+          subject.expand(["**/#{current_file_basename}", "foo.cr"])
+        end
+      end
     end
   end
 end