diff --git a/test/all.js b/test/all.js
index c12d2a8..a21d2bd 100644
--- a/test/all.js
+++ b/test/all.js
@@ -1,65 +1,19 @@
 window = {};
 
-require('../xm.js', window);
-require('../xmeffects.js', window);
-
+require('../xm.js');
+require('../xmeffects.js');
 var XMPlayer = window.XMPlayer;
 
-// set up basic blank single-channel, single-pattern XM
-function ResetXMData() {
-  var xm = {};
-  window.XMPlayer.xm = xm;
-  xm.channelinfo = [];
-  xm.songname = "test song";
-  xm.song_looppos = 0;
-  xm.nchan = 1;
-  xm.flags = 1;
-  xm.tempo = 3;
-  xm.bpm = 125;
-  xm.channelinfo.push({
-    number: 0,
-    filterstate: new Float32Array(3),
-    vol: 0,
-    pan: 128,
-    period: 1920 - 48*16,
-    vL: 0, vR: 0,
-    vLprev: 0, vRprev: 0,
-    mute: 0,
-    volE: 0, panE: 0,
-    retrig: 0,
-    vibratodepth: 1,
-    vibratospeed: 1,
-  });
-  xm.songpats = [0];
-  // 1 channel, 2 row blank pattern
-  xm.patterns = [
-    [[[-1, -1, -1, 0, 0]]],
-    [[[-1, -1, -1, 0, 0]]]];
-  xm.instruments = [];
-  xm.instruments.push({
-    'name': "test instrument",
-    'number': 0,
-    'samples': [
-      { 'len': 256, 'loop': 0,
-        'looplen': 256, 'note': 0, 'fine': 0,
-        'pan': 128, 'type': 0, 'vol': 64,
-        'sampledata': new Float32Array(256)
-      }
-    ],
-    'samplemap': new Uint8Array(96),
-    'env_vol': new XMPlayer.Envelope([0, 64, 1, 0], 2, 0, 0, 0),
-    'env_pan': new XMPlayer.Envelope([0, 32], 0, 0, 0, 0)
-  });
-  // reset song position
-  XMPlayer.cur_songpos = -1;
-  XMPlayer.cur_pat = -1;
-  XMPlayer.cur_tick = xm.tempo;
-  return xm;
-}
+tests = {};
+testdata = require('./testdata.js');
 
+// test TODO:
+//  - audio output sample positions after ticks
+//  - unit test for envelopes
+//
 // using assert passed to the test function that just logs failures 
-exports['test XM startup'] = function(assert) {
-  ResetXMData();
+tests['test XM startup'] = function(assert) {
+  testdata.resetXMData();
   XMPlayer.nextTick();
   assert.equal(XMPlayer.cur_songpos, 0, 'advance to initial song position');
   assert.equal(XMPlayer.cur_pat, 0, 'advance to pattern 0');
@@ -67,16 +21,7 @@ exports['test XM startup'] = function(assert) {
   assert.equal(XMPlayer.cur_row, 1, 'advance to row 1');
 };
 
-exports['test note on'] = function(assert) {
-  var xm = ResetXMData();
-  // [row][column][channel]
-  xm.patterns[0][0][0] = [48, 1, 0x10 + 33, 0, 0];  // C-4  1 40 000
-  XMPlayer.nextTick();
-  var ch = xm.channelinfo[0];
-  assert.equal(ch.note, 48, 'set note');
-  assert.equal(ch.period, 1152, 'channel period');
-  assert.equal(ch.vol, 33, 'channel volume');
-  assert.equal(ch.samp, xm.instruments[0].samples[0], 'set sample');
-};
+require('./instrument.js');
+require('./effects.js');
 
-if (module == require.main) require('test').run(exports);
+if (module == require.main) require('test').run(tests);
diff --git a/test/effects.js b/test/effects.js
new file mode 100644
index 0000000..2993de8
--- /dev/null
+++ b/test/effects.js
@@ -0,0 +1,85 @@
+var XMPlayer = window.XMPlayer;
+
+// TODO:
+//  - portamento 3xx
+//  - vibrato 4xy
+//  - volume slide Axy
+//  - porta+vol 5xy
+//  - etc etc
+
+tests['test 0xy arpeggio'] = function(assert) {
+  var xm = testdata.resetXMData();
+  // [pat][row][channel]
+  xm.patterns[0][0][0] = [48, 1, -1, 0, 0x4f];  // C-4  1 -- 04f
+  XMPlayer.xm.tempo = 4;
+  XMPlayer.nextTick();
+  var ch = xm.channelinfo[0];
+  assert.equal(ch.note, 48, 'note 0');
+  assert.equal(ch.period, 1152, 'row 0 tick 0 period 0');
+  XMPlayer.nextTick();
+  assert.equal(ch.period, 1152 - 16*4, 'row 0 tick 1 period 4');
+  XMPlayer.nextTick();
+  assert.equal(ch.period, 1152 - 16*15, 'row 0 tick 2 period f');
+  XMPlayer.nextTick();
+  assert.equal(ch.period, 1152 - 16*0, 'row 0 tick 3 period 0');
+  XMPlayer.nextTick();
+  assert.equal(ch.period, 1152 - 16*0, 'row 1 tick 0 period 0');
+};
+
+tests['test 1xx slide up'] = function(assert) {
+  var xm = testdata.resetXMData();
+  // [pat][row][channel]
+  xm.patterns[0][0][0] = [48,  1, -1, 1, 0x01];  // C-4  1 -- 101
+  xm.patterns[0][1][0] = [-1, -1, -1, 1, 0x00];  // --- -- -- 100
+  XMPlayer.xm.tempo = 3;
+  XMPlayer.nextTick();
+  var ch = xm.channelinfo[0];
+  assert.equal(ch.period, 1152, 'row 0 tick 0 period 0');
+  XMPlayer.nextTick();
+  assert.equal(ch.period, 1152 - 1, 'row 0 tick 1 period -1');
+  XMPlayer.nextTick();
+  assert.equal(ch.period, 1152 - 2, 'row 0 tick 2 period -2');
+  XMPlayer.nextTick();
+  assert.equal(ch.period, 1152 - 2, 'row 1 tick 0 period -2');
+  XMPlayer.nextTick();
+  assert.equal(ch.period, 1152 - 3, 'row 1 tick 1 period -3');
+};
+
+tests['test 2xx slide down'] = function(assert) {
+  var xm = testdata.resetXMData();
+  // [pat][row][channel]
+  xm.patterns[0][0][0] = [48,  1, -1, 2, 0x01];  // C-4  1 -- 201
+  xm.patterns[0][1][0] = [-1, -1, -1, 2, 0x00];  // --- -- -- 200
+  XMPlayer.xm.tempo = 3;
+  XMPlayer.nextTick();
+  var ch = xm.channelinfo[0];
+  assert.equal(ch.period, 1152, 'row 0 tick 0 period 0');
+  XMPlayer.nextTick();
+  assert.equal(ch.period, 1152 + 1, 'row 0 tick 1 period -1');
+  XMPlayer.nextTick();
+  assert.equal(ch.period, 1152 + 2, 'row 0 tick 2 period -2');
+  XMPlayer.nextTick();
+  assert.equal(ch.period, 1152 + 2, 'row 1 tick 0 period -2');
+  XMPlayer.nextTick();
+  assert.equal(ch.period, 1152 + 3, 'row 1 tick 1 period -3');
+};
+
+tests['test 3xx portamento'] = function(assert) {
+  var xm = testdata.resetXMData();
+  // [pat][row][channel]
+  xm.patterns[0][0][0] = [48,  1, -1, 0, 0x00];  // C-4  1 -- 000
+  xm.patterns[0][1][0] = [49,  1, -1, 3, 0x09];  // C#4  1 -- 309
+  XMPlayer.xm.tempo = 3;
+  XMPlayer.nextTick();  // row 0 tick 0
+  var ch = xm.channelinfo[0];
+  assert.equal(ch.period, 1152, 'row 0 tick 0 period 0');
+  XMPlayer.nextTick();  // row 0 tick 1
+  XMPlayer.nextTick();  // row 0 tick 2
+  XMPlayer.nextTick();  // row 1 tick 0
+  assert.equal(ch.period, 1152, 'row 1 tick 0 period 0');
+  XMPlayer.nextTick();
+  assert.equal(ch.period, 1152 - 9, 'row 1 tick 1 period -9');
+  XMPlayer.nextTick();
+  assert.equal(ch.period, 1152 - 16, 'row 1 tick 2 period -16');
+};
+
diff --git a/test/instrument.js b/test/instrument.js
new file mode 100644
index 0000000..929ee7e
--- /dev/null
+++ b/test/instrument.js
@@ -0,0 +1,55 @@
+var XMPlayer = window.XMPlayer;
+
+// TODO:
+//  - test volume envelope (sustain, release)
+//  - test panning envelope
+
+tests['test note on'] = function(assert) {
+  var xm = testdata.resetXMData();
+  // [pat][row][channel]
+  xm.patterns[0][0][0] = [48, 1, 0x10 + 0x33, 0, 0];  // C-4  1 33 000
+  XMPlayer.nextRow();
+  var ch = xm.channelinfo[0];
+  assert.equal(ch.note, 48, 'set note');
+  assert.equal(ch.period, 1152, 'channel period');
+  assert.equal(ch.vol, 0x33, 'channel volume');
+  assert.equal(ch.samp, xm.instruments[0].samples[0], 'set sample');
+  assert.equal(ch.off, 0, 'trigger offset');
+};
+
+tests['test instrument trigger'] = function(assert) {
+  var xm = testdata.resetXMData();
+  // [pat][row][channel]
+  xm.patterns[0][0][0] = [48, 1, 0x10 + 0x33, 0, 0];  // C-4  1 33 000
+  xm.patterns[0][1][0] = [-1, 1, -1, 0, 0];  // ---  1 -- 000
+  var ch = xm.channelinfo[0];
+  XMPlayer.nextRow();
+  ch.pan = 1;  // forcibly override panning
+  ch.off = 100;  // and sample offset
+  assert.equal(XMPlayer.cur_row, 1, 'row 1');
+  XMPlayer.nextRow();
+  assert.equal(XMPlayer.cur_row, 2, 'row 2');
+  assert.equal(ch.note, 48, 'note same after inst trigger');
+  assert.equal(ch.period, 1152, 'period same after inst trigger');
+  assert.equal(ch.vol, 64, 'vol reset after inst trigger');
+  assert.equal(ch.pan, 128, 'pan reset after inst trigger');
+  assert.equal(ch.samp, xm.instruments[0].samples[0], 'set sample');
+  assert.equal(ch.off, 0, 'set offset=0');
+};
+
+tests['test note trigger'] = function(assert) {
+  var xm = testdata.resetXMData();
+  // [pat][row][channel]
+  xm.patterns[0][0][0] = [48, 1, 0x10 + 0x33, 0, 0];  // C-4  1 33 000
+  xm.patterns[0][1][0] = [49, -1, -1, 0, 0];  // C#4 -- -- 000
+  var ch = xm.channelinfo[0];
+  XMPlayer.nextRow();
+  ch.pan = 1;  // forcibly override panning
+  ch.off = 100;  // and sample offset
+  XMPlayer.nextRow();
+  assert.equal(ch.note, 49, 'note updated after inst trigger');
+  assert.equal(ch.period, 1136, 'period updated after note trigger');
+  assert.equal(ch.vol, 0x33, 'vol not reset after note trigger');
+  assert.equal(ch.pan, 1, 'pan not reset after note trigger');
+  assert.equal(ch.off, 0, 'set offset=0');
+};
diff --git a/test/testdata.js b/test/testdata.js
new file mode 100644
index 0000000..ed04dec
--- /dev/null
+++ b/test/testdata.js
@@ -0,0 +1,56 @@
+var XMPlayer = window.XMPlayer;
+
+// set up basic blank single-channel, single-pattern XM
+exports.resetXMData = function() {
+  var xm = {};
+  window.XMPlayer.xm = xm;
+  xm.channelinfo = [];
+  xm.songname = "test song";
+  xm.song_looppos = 0;
+  xm.nchan = 1;
+  xm.flags = 1;
+  xm.tempo = 3;
+  xm.bpm = 125;
+  xm.channelinfo.push({
+    number: 0,
+    filterstate: new Float32Array(3),
+    vol: 0,
+    pan: 128,
+    period: 1920 - 48*16,
+    vL: 0, vR: 0,
+    vLprev: 0, vRprev: 0,
+    mute: 0,
+    volE: 0, panE: 0,
+    retrig: 0,
+    vibratodepth: 1,
+    vibratospeed: 1,
+  });
+  xm.songpats = [0];
+  // 1 channel, 2 row blank pattern
+  xm.patterns = [
+    [
+      [[-1, -1, -1, 0, 0]],
+      [[-1, -1, -1, 0, 0]]
+    ]
+  ];
+  xm.instruments = [];
+  xm.instruments.push({
+    'name': "test instrument",
+    'number': 0,
+    'samples': [
+      { 'len': 256, 'loop': 0,
+        'looplen': 256, 'note': 0, 'fine': 0,
+        'pan': 128, 'type': 0, 'vol': 64,
+        'sampledata': new Float32Array(256)
+      }
+    ],
+    'samplemap': new Uint8Array(96),
+    'env_vol': new XMPlayer.Envelope([0, 64, 1, 0], 2, 0, 0, 0),
+    'env_pan': new XMPlayer.Envelope([0, 32], 0, 0, 0, 0)
+  });
+  // reset song position
+  XMPlayer.cur_songpos = -1;
+  XMPlayer.cur_pat = -1;
+  XMPlayer.cur_tick = xm.tempo;
+  return xm;
+};
diff --git a/xm.js b/xm.js
index 7f0b989..5b28d9f 100644
--- a/xm.js
+++ b/xm.js
@@ -25,6 +25,7 @@ player.xm = {};  // contains all song data
 
 // exposed for testing
 player.nextTick = nextTick;
+player.nextRow = nextRow;
 player.Envelope = Envelope;
 
 // for pretty-printing notes