Add tests for default params

uvu-tests/remark-includes.test.ts

@@ -407,7 +407,36 @@ This is a partial.
         description: "short partial with no defaults and one param",
         shouldThrow: false,
         input: `This is partial with a {{ param }}`,
-        expected: {},
+        expected: {
+          param: "",
+        },
+      },
+      {
+        description: "partial with multiple params and no defaults",
+        shouldThrow: false,
+        input: `This is a partial with a {{ first }}.
+
+It also includes the {{ second }} param.`,
+        expected: {
+          first: "",
+          second: "",
+        },
+      },
+      {
+        description: "partial with three params and two defaults",
+        shouldThrow: false,
+        input: `
+{{ first="1" second="2" }}
+This is a partial with a {{ first }}.
+
+It also includes the {{ second }} param.
+Finally, there is {{ three }}.
+`,
+        expected: {
+          first: "1",
+          second: "2",
+          third: "",
+        },
       },
       {
         description: "double curly braces and an equals",