test: cover normalizePagePayloadForNativeLoad edge cases

CHANGELOG.md

@@ -2,6 +2,11 @@
 
 All notable changes to `@mathnotes/mobile-ink` will be documented here.
 
+## [Unreleased]
+
+- Added unit tests for `normalizePagePayloadForNativeLoad` covering blank, malformed, and valid native-load payloads (#12).
+
+
 ## [0.3.4] - 2026-08-15
 
 - Added the optional `overlay` prop to `InfiniteInkCanvas`. Host applications

src/__tests__/payloadNormalization.test.ts

@@ -0,0 +1,122 @@
+/**
+ * Tests for normalizePagePayloadForNativeLoad.
+ *
+ * Native loads must only accept object payloads with a pages map. Everything
+ * else is either normalized to a blank notebook or rejected as unsafe.
+ */
+
+import { normalizePagePayloadForNativeLoad } from '../payload';
+
+const BLANK_PAGE_PAYLOAD = '{"pages":{}}';
+
+describe('normalizePagePayloadForNativeLoad', () => {
+  describe('blank payloads', () => {
+    it.each([
+      ['null', null],
+      ['undefined', undefined],
+      ['empty string', ''],
+      ['whitespace only', '   \n\t  '],
+    ] as const)('treats %s as a valid blank load', (_label, input) => {
+      const result = normalizePagePayloadForNativeLoad(input);
+
+      expect(result).toEqual({
+        isValid: true,
+        normalizedPayload: BLANK_PAGE_PAYLOAD,
+        reasonCode: 'blank_payload',
+      });
+    });
+  });
+
+  describe('invalid JSON and non-object roots', () => {
+    it('rejects unparseable JSON as unsafe', () => {
+      const result = normalizePagePayloadForNativeLoad('{not-json');
+
+      expect(result.isValid).toBe(false);
+      expect(result.normalizedPayload).toBe(BLANK_PAGE_PAYLOAD);
+      expect(result.reasonCode).toBe('json_parse_failed');
+    });
+
+    it.each([
+      ['array root', '[]'],
+      ['array with objects', '[{"pages":{}}]'],
+      ['string root', '"pages"'],
+      ['number root', '42'],
+      ['boolean root', 'true'],
+      ['null root', 'null'],
+    ])('rejects %s (payload_not_object)', (_label, input) => {
+      const result = normalizePagePayloadForNativeLoad(input);
+
+      expect(result.isValid).toBe(false);
+      expect(result.normalizedPayload).toBe(BLANK_PAGE_PAYLOAD);
+      expect(result.reasonCode).toBe('payload_not_object');
+    });
+  });
+
+  describe('missing or invalid pages', () => {
+    it.each([
+      ['missing pages key', '{"version":"1.0"}'],
+      ['pages null', '{"pages":null}'],
+      ['pages array', '{"pages":[]}'],
+      ['pages string', '{"pages":"nope"}'],
+      ['pages number', '{"pages":1}'],
+    ])('normalizes %s to blank with missing_pages', (_label, input) => {
+      const result = normalizePagePayloadForNativeLoad(input);
+
+      // Safe to load as blank; not a hard reject (legacy / empty notebooks).
+      expect(result.isValid).toBe(true);
+      expect(result.normalizedPayload).toBe(BLANK_PAGE_PAYLOAD);
+      expect(result.reasonCode).toBe('missing_pages');
+    });
+  });
+
+  describe('valid payloads', () => {
+    it('accepts object payload with empty pages map', () => {
+      const input = '{"pages":{}}';
+      const result = normalizePagePayloadForNativeLoad(input);
+
+      expect(result.isValid).toBe(true);
+      expect(result.normalizedPayload).toBe(input);
+      expect(result.reasonCode).toBeUndefined();
+    });
+
+    it('accepts object payload with page entries and preserves original text', () => {
+      const input =
+        '{"pages":{"page-1":{"strokes":[]}},"version":"1.0"}';
+      const result = normalizePagePayloadForNativeLoad(input);
+
+      expect(result.isValid).toBe(true);
+      expect(result.normalizedPayload).toBe(input);
+      expect(result.reasonCode).toBeUndefined();
+    });
+
+    it('trims surrounding whitespace but keeps the JSON body', () => {
+      const body = '{"pages":{"a":{}}}';
+      const result = normalizePagePayloadForNativeLoad(`  \n${body}\t`);
+
+      expect(result.isValid).toBe(true);
+      expect(result.normalizedPayload).toBe(body);
+      expect(result.reasonCode).toBeUndefined();
+    });
+  });
+
+  describe('safety invariants', () => {
+    it('never returns a non-blank normalized payload when isValid is false', () => {
+      const badInputs = [
+        '{',
+        '[]',
+        'null',
+        '1',
+        '"x"',
+        'true',
+        'not json at all',
+      ];
+
+      for (const input of badInputs) {
+        const result = normalizePagePayloadForNativeLoad(input);
+        if (!result.isValid) {
+          expect(result.normalizedPayload).toBe(BLANK_PAGE_PAYLOAD);
+        }
+      }
+    });
+  });
+});