Fix transition.on(typename, null).

Also, tests for transition.remove. #20

src/transition/on.js

@@ -9,7 +9,6 @@ function start(name) {
 }
 
 function onFunction(id, name, listener) {
-  if (typeof listener !== "function") throw new Error;
   var on0, on1, sit = start(name) ? init : set;
   return function() {
     var schedule = sit(this, id),

test/transition/attrTween-test.js

@@ -86,7 +86,7 @@ tape("transition.attrTween(name, value) coerces the specified name to a string",
 tape("transition.attrTween(name, value) throws an error if value is not null and not a function", function(test) {
   var root = jsdom.jsdom().documentElement,
       transition = d3_selection.select(root).transition();
-  test.throws(function() { transition.attrTween("foo", 42); }, /Error/);
+  test.throws(function() { transition.attrTween("foo", 42); });
   test.end();
 });
 

test/transition/ease-test.js

@@ -28,8 +28,8 @@ tape("transition.ease() returns the easing function for the first non-null node"
 tape("transition.ease(ease) throws an error if ease is not a function", function(test) {
   var root = jsdom.jsdom().documentElement,
       transition = d3_selection.select(root).transition();
-  test.throws(function() { transition.ease(42); }, /Error/);
-  test.throws(function() { transition.ease(null); }, /Error/);
+  test.throws(function() { transition.ease(42); });
+  test.throws(function() { transition.ease(null); });
   test.end();
 });
 

test/transition/merge-test.js

@@ -24,6 +24,6 @@ tape("transition.merge(other) throws an error if the other transition has a diff
       two = document.querySelector("#two"),
       transition1 = d3_selection.selectAll([null, two]).transition(),
       transition2 = d3_selection.selectAll([one, null]).transition();
-  test.throws(function() { transition1.merge(transition2); }, /Error/);
+  test.throws(function() { transition1.merge(transition2); });
   test.end();
 });

test/transition/on-test.js

@@ -8,7 +8,7 @@ require("../../");
 tape("transition.on(type, listener) throws an error if listener is not a function", function(test) {
   var root = jsdom.jsdom().documentElement,
       transition = d3_selection.select(root).transition();
-  test.throws(function() { transition.on("start", 42); }, /Error/);
+  test.throws(function() { transition.on("start", 42); });
   test.end();
 });
 
@@ -27,17 +27,40 @@ tape("transition.on(typename) returns the listener with the specified typename,
 tape("transition.on(typename) throws an error if the specified type is not supported", function(test) {
   var root = jsdom.jsdom().documentElement,
       transition = d3_selection.select(root).transition();
-  test.throws(function() { transition.on("foo"); }, /Error/);
+  test.throws(function() { transition.on("foo"); });
   test.end();
 });
 
 tape("transition.on(typename, listener) throws an error if the specified type is not supported", function(test) {
   var root = jsdom.jsdom().documentElement,
       transition = d3_selection.select(root).transition();
-  test.throws(function() { transition.on("foo", function() {}); }, /Error/);
+  test.throws(function() { transition.on("foo", function() {}); });
   test.end();
 });
 
+tape("transition.on(typename, listener) throws an error if the specified listener is not a function", function(test) {
+  var root = jsdom.jsdom().documentElement,
+      transition = d3_selection.select(root).transition();
+  test.throws(function() { transition.on("foo", 42); });
+  test.end();
+});
+
+tape("transition.on(typename, null) removes the listener with the specified typename, if any", function(test) {
+  var root = jsdom.jsdom().documentElement,
+      starts = 0,
+      transition = d3_selection.select(root).transition().on("start.foo", function() { ++starts; }),
+      schedule = root.__transition[transition._id];
+
+  test.equal(transition.on("start.foo", null), transition);
+  test.equal(transition.on("start.foo"), undefined);
+  test.equal(schedule.on.on("start.foo"), undefined);
+
+  d3_timer.timeout(function() {
+    test.equal(starts, 0);
+    test.end();
+  });
+});
+
 tape("transition.on(\"start\", listener) registers a listener for the start event", function(test) {
   var root = jsdom.jsdom().documentElement,
       transition = d3_selection.select(root).transition().on("start", started),

test/transition/remove-test.js

@@ -0,0 +1,49 @@
+var tape = require("tape"),
+    jsdom = require("jsdom"),
+    d3_timer = require("d3-timer"),
+    d3_selection = require("d3-selection");
+
+require("../../");
+
+tape("transition.remove() creates an end listener to remove the element", function(test) {
+  var document = jsdom.jsdom(),
+      root = document.documentElement,
+      body = document.body,
+      selection = d3_selection.select(body),
+      transition = selection.transition().remove().on("start", started).on("end", ended);
+
+  function started() {
+    test.equal(body.parentNode, root);
+  }
+
+  function ended() {
+    test.equal(body.parentNode, null);
+    test.end();
+  }
+
+  d3_timer.timeout(function(elapsed) {
+    test.equal(body.parentNode, root);
+  });
+});
+
+tape("transition.remove() creates an end listener named end.remove", function(test) {
+  var document = jsdom.jsdom(),
+      root = document.documentElement,
+      body = document.body,
+      selection = d3_selection.select(body),
+      transition = selection.transition().remove().on("start", started).on("end", ended);
+
+  transition.on("end.remove").call(body);
+  test.equal(body.parentNode, null);
+  transition.on("end.remove", null);
+  root.appendChild(body);
+
+  function started() {
+    test.equal(body.parentNode, root);
+  }
+
+  function ended() {
+    test.equal(body.parentNode, root);
+    test.end();
+  }
+});

test/transition/styleTween-test.js

@@ -90,7 +90,7 @@ tape("transition.styleTween(name, value) coerces the specified name to a string"
 tape("transition.styleTween(name, value) throws an error if value is not null and not a function", function(test) {
   var root = jsdom.jsdom().documentElement,
       transition = d3_selection.select(root).transition();
-  test.throws(function() { transition.styleTween("color", 42); }, /Error/);
+  test.throws(function() { transition.styleTween("color", 42); });
   test.end();
 });
 

test/transition/tween-test.js

@@ -125,7 +125,7 @@ tape("transition.tween(name) coerces the specified name to a string", function(t
 tape("transition.tween(name, value) throws an error if value is not null and not a function", function(test) {
   var root = jsdom.jsdom().documentElement,
       transition = d3_selection.select(root).transition();
-  test.throws(function() { transition.tween("foo", 42); }, /Error/);
+  test.throws(function() { transition.tween("foo", 42); });
   test.end();
 });