diff --git a/packages/core/vitest/drawLine.test.mjs b/packages/core/vitest/drawLine.test.mjs
new file mode 100644
index 00000000..84359a7c
--- /dev/null
+++ b/packages/core/vitest/drawLine.test.mjs
@@ -0,0 +1,46 @@
+/*
+drawLine.test.mjs - <short description TODO>
+Copyright (C) 2022 Strudel contributors - see <https://github.com/tidalcycles/strudel/blob/main/packages/core/test/drawLine.test.mjs>
+This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for more details. You should have received a copy of the GNU Affero General Public License along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+import { fastcat, stack, slowcat, silence, pure } from '../pattern.mjs';
+import { describe, it, expect } from 'vitest';
+import drawLine from '../drawLine.mjs';
+
+describe('drawLine', () => {
+  it('supports equal lengths', () => {
+    expect(drawLine(fastcat(0), 4)).toEqual('|0|0');
+    expect(drawLine(fastcat(0, 1), 4)).toEqual('|01|01');
+    expect(drawLine(fastcat(0, 1, 2), 6)).toEqual('|012|012');
+  });
+  it('supports unequal lengths', () => {
+    expect(drawLine(fastcat(0, [1, 2]), 10)).toEqual('|0-12|0-12');
+    expect(drawLine(fastcat(0, [1, 2, 3]), 10)).toEqual('|0--123|0--123');
+    expect(drawLine(fastcat(0, 1, [2, 3]), 10)).toEqual('|0-1-23|0-1-23');
+  });
+  it('supports unequal silence', () => {
+    expect(drawLine(fastcat(0, silence, [1, 2]), 10)).toEqual('|0-..12|0-..12');
+  });
+  it('supports polyrhythms', () => {
+    // assert.equal(drawLine(fastcat(pure(0).fast(2), pure(1).fast(3)), 10), '|0--0--1-1-1-');
+    expect(drawLine(fastcat(pure(0).fast(2), pure(1).fast(3)), 10)).toEqual('|0--0--1-1-1-');
+  });
+  it('supports multiple lines', () => {
+    expect(drawLine(fastcat(0, stack(1, 2)), 10)).toEqual(`|01|01|01|01
+|.2|.2|.2|.2`);
+
+    expect(drawLine(fastcat(0, 1, stack(2, 3)), 10)).toEqual(`|012|012|012
+|..3|..3|..3`);
+
+    expect(drawLine(fastcat(0, stack(1, 2, 3)), 10)).toEqual(`|01|01|01|01
+|.2|.2|.2|.2
+|.3|.3|.3|.3`);
+    expect(drawLine(fastcat(0, 1, stack(2, 3, 4)), 10)).toEqual(`|012|012|012
+|..3|..3|..3
+|..4|..4|..4`);
+  });
+  it('supports unequal cycle lengths', () => {
+    expect(drawLine(slowcat(0, [1, 2]), 10)).toEqual(`|0|12|0|12`);
+  });
+});
diff --git a/packages/core/vitest/fraction.test.mjs b/packages/core/vitest/fraction.test.mjs
new file mode 100644
index 00000000..6b710d04
--- /dev/null
+++ b/packages/core/vitest/fraction.test.mjs
@@ -0,0 +1,15 @@
+/*
+fraction.test.mjs - <short description TODO>
+Copyright (C) 2022 Strudel contributors - see <https://github.com/tidalcycles/strudel/blob/main/packages/core/test/fraction.test.mjs>
+This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for more details. You should have received a copy of the GNU Affero General Public License along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+import Fraction, { gcd } from '../fraction.mjs';
+import { describe, it, expect } from 'vitest';
+
+describe('gcd', () => {
+  it('should work', () => {
+    const F = Fraction._original;
+    expect(gcd(F(1 / 6), F(1 / 4)).toFraction()).toEqual('1/12');
+  });
+});