Stringify HP in tests for the toString functionality

src/battlers/HitPoints.test.ts

@@ -41,7 +41,7 @@ describe("hitPointsWithoutConfidenceToString", () => {
         [{currentHealth: -25, maxHealth: 0, maxConfidence: -200}, "{Health: -25/0, Confidence: -/-/-200}"],
     ]
     pairs.forEach(([hp, expected]) => {
-        test(`for ${hp} = "${expected}"`, () => {
+        test(`for ${JSON.stringify(hp)} = "${expected}"`, () => {
             expect(hitPointsWithoutConfidenceToString(hp)).toStrictEqual(expected)
         })
     })
@@ -53,7 +53,7 @@ describe("hitPointsToString", () => {
         [{currentHealth: -25, maxHealth: 0, maxConfidence: -200, currentConfidence: -15}, "{Health: -25/0, Confidence: -15/<err>/-200}"],
     ]
     pairs.forEach(([hp, expected]) => {
-        test(`for ${hp} = "${expected}"`, () => {
+        test(`for ${JSON.stringify(hp)} = "${expected}"`, () => {
             expect(hitPointsToString(hp)).toStrictEqual(expected)
         })
     })