fix: add grace validation test and enforce range check

Author: pari7maheshwari

app/api/streak/route.test.ts

@@ -163,6 +163,24 @@ describe('GET /api/streak', () => {
       expect(fetchGitHubContributions).not.toHaveBeenCalled();
     });
 
+    it('returns 400 when grace is below the minimum value', async () => {
+      const response = await GET(
+        makeRequest({
+          user: 'octocat',
+          grace: '-1',
+        })
+      );
+
+      expect(response.status).toBe(400);
+
+      const body = await response.json();
+
+      expect(body.error).toBe('Invalid parameters');
+      expect(body.details.fieldErrors.grace[0]).toBe('grace must be an integer between 0 and 7');
+
+      expect(fetchGitHubContributions).not.toHaveBeenCalled();
+    });
+
     it('should return 200 OK and valid SVG when the optional repo query parameter is provided', async () => {
       // 1. Make request with both parameters present
       const response = await GET(makeRequest({ user: 'octocat', repo: 'commitpulse' }));
@@ -246,18 +264,15 @@ describe('GET /api/streak', () => {
       expect(fetchGitHubContributions).toHaveBeenCalled();
     });
 
-    it('returns valid SVG when grace exceeds max value', async () => {
+    it('returns 400 when grace exceeds max value', async () => {
       const response = await GET(
         makeRequest({
           user: 'octocat',
           grace: '999',
         })
       );
 
-      expect(response.status).toBe(200);
-
-      const body = await response.text();
-      expect(body).toContain('<svg');
+      expect(response.status).toBe(400);
     });
 
     it('embeds the username (uppercased) in the SVG title', async () => {

lib/validations.test.ts

@@ -113,6 +113,20 @@ describe('streakParamsSchema', () => {
     }
   });
 
+  it('should fail when grace is below the minimum value of 0', () => {
+    const result = streakParamsSchema.safeParse({
+      user: 'octocat',
+      grace: '-1',
+    });
+
+    expect(result.success).toBe(false);
+    if (!result.success) {
+      expect(result.error.flatten().fieldErrors.grace?.[0]).toBe(
+        'grace must be an integer between 0 and 7'
+      );
+    }
+  });
+
   it('accepts a valid width value', () => {
     const result = streakParamsSchema.safeParse({
       user: 'octocat',

lib/validations.ts

@@ -178,7 +178,19 @@ export const streakParamsSchema = z.object({
   delta_format: z.enum(['percent', 'absolute', 'both']).catch('percent').default('percent'),
   width: dimensionParam('width', 100, 1200),
   height: dimensionParam('height', 80, 800),
-  grace: z.string().optional().transform(toGraceValue).default(1),
+  grace: z
+    .string()
+    .optional()
+    .refine(
+      (val) => {
+        if (!val) return true;
+        const parsed = Number(val);
+        return !isNaN(parsed) && Number.isInteger(parsed) && parsed >= 0 && parsed <= 7;
+      },
+      { message: 'grace must be an integer between 0 and 7' }
+    )
+    .transform(toGraceValue)
+    .default(1),
   mode: z.enum(['commits', 'loc']).catch('commits').default('commits'),
   repo: z.string().optional(),
   org: z