Merge pull request #60 from vslinko-forks/master

First and last arguments must be positive integers

Author: wincent

src/connection/__tests__/arrayconnection.js

@@ -470,20 +470,22 @@ describe('connectionFromArray()', () => {
   });
 
   describe('cursor edge cases', () => {
-    it('returns no elements if first is 0', () => {
-      var c = connectionFromArray(
-        letters,
-        {first: 0}
-      );
-      return expect(c).to.deep.equal({
-        edges: [],
-        pageInfo: {
-          startCursor: null,
-          endCursor: null,
-          hasPreviousPage: false,
-          hasNextPage: true,
-        }
-      });
+    it('throws an error if first < 0', () => {
+      expect(() => {
+        connectionFromArray(
+          letters,
+          {first: -1}
+        );
+      }).to.throw('Argument "first" must be a non-negative integer');
+    });
+
+    it('throws an error if last < 0', () => {
+      expect(() => {
+        connectionFromArray(
+          letters,
+          {last: -1}
+        );
+      }).to.throw('Argument "last" must be a non-negative integer');
     });
 
     it('returns all elements if cursors are invalid', () => {

src/connection/arrayconnection.js

@@ -85,12 +85,20 @@ export function connectionFromArraySlice<T>(
     arrayLength
   );
   if (typeof first === 'number') {
+    if (first < 0) {
+      throw new Error('Argument "first" must be a non-negative integer');
+    }
+
     endOffset = Math.min(
       endOffset,
       startOffset + first
     );
   }
   if (typeof last === 'number') {
+    if (last < 0) {
+      throw new Error('Argument "last" must be a non-negative integer');
+    }
+
     startOffset = Math.max(
       startOffset,
       endOffset - last