Fix bug in Fraction.lcm (#1133)

* bugfix lcm

packages/core/fraction.mjs

@@ -119,10 +119,10 @@ export const lcm = (...fractions) => {
   if (fractions.length === 0) {
     return undefined;
   }
-
+  const x = fractions.pop();
   return fractions.reduce(
     (lcm, fraction) => (lcm === undefined || fraction === undefined ? undefined : lcm.lcm(fraction)),
-    fraction(1),
+    x,
   );
 };
 

packages/core/test/pattern.test.mjs

@@ -1209,4 +1209,40 @@ describe('Pattern', () => {
       }
     });
   });
+  describe('s_expand', () => {
+    it('can expand four things in half', () => {
+      expect(
+        sameFirst(
+          sequence(0, 1, 2, 3).s_expand(1, 0.5),
+          s_cat(sequence(0, 1, 2, 3), sequence(0, 1, 2, 3).s_expand(0.5)),
+        ),
+      );
+    });
+    it('can expand five things in half', () => {
+      expect(
+        sameFirst(
+          sequence(0, 1, 2, 3, 4).s_expand(1, 0.5),
+          s_cat(sequence(0, 1, 2, 3, 4), sequence(0, 1, 2, 3, 4).s_expand(0.5)),
+        ),
+      );
+    });
+  });
+  describe('stepJoin', () => {
+    it('can join a pattern with a tactus of 2', () => {
+      expect(
+        sameFirst(
+          sequence(pure(pure('a')), pure(pure('b').setTactus(2))).stepJoin(),
+          s_cat(pure('a'), pure('b').setTactus(2)),
+        ),
+      );
+    });
+    it('can join a pattern with a tactus of 0.5', () => {
+      expect(
+        sameFirst(
+          sequence(pure(pure('a')), pure(pure('b').setTactus(0.5))).stepJoin(),
+          s_cat(pure('a'), pure('b').setTactus(0.5)),
+        ),
+      );
+    });
+  });
 });