View Debug Output

Randy Merrill edited this page Feb 20, 2012 · 1 revision
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Viewing Output

When writing unit tests, particularly with TDD, sometimes you need to see your data. Maybe you’re working on a complex regular expression and you’re building it up iteratively, watching the string mutate as you change the regex. Maybe you need to visualize the structure of a complex, uh, structure. Maybe when an error occurs, you actually want to see the entire cfcatch struct because you have so far failed in your mission to jack into the ether and absorb the bits and bytes into your neurons. Maybe you just want to see the damn query.

Typically, this is pretty annoying to do in unit tests. Sometimes, it’s just not possible if the framework doesn’t make it easy for you. So you end up writing little tester files that create the object you’re working with, do a cfdump or something, and then throw that work away when you’ve seen what you need to see. Icckkkkkk.

MXUnit makes seeing your data easy. In fact, making things easier is one of our core tenets. With MXUnit, you can use CFOUTPUT and CFDUMP inside the test cases themselves. But there’s an even better way to see your data: debug().

Why is it better? If you use cfoutput and cfdump inside your tests, you’ll only see that output if the test passes. But with debug(), you’re guaranteed to see the output of any debug() calls, even if the test fails\! Of course, any calls to debug() after a failed assertion won’t show up, because as soon as an assertion fails the test method stops executing.

How to use debug()

">	<cffunction name="testExecuteTestCase" returntype="void" hint="">
		<cfset var name = "mxunit.PluginDemoTests.DoubleMethodTest">
		<cfset var methods = "">
		<cfset var results = "">

		<cfset results = rf.executeTestCase(name,methods,"")>
		<cfset methods = rf.getComponentMethods(name)>

		<cfset debug(results)>

		<cfset assertTrue(isStruct(results),"results should be struct")>
		<cfset assertEquals(ArrayLen(methods),ArrayLen(StructKeyArray(results[[name])),"")>

You can use debug() anywhere you’d normally use CFDUMP.
  1. Caveat: No promises on how it’ll behave if you try to call debug() on components and then run the test in the Eclipse plugin. You’re bound to get an axis/webservice/xml parse error of some form or another.
  2. Caveat: if you’re calling debug() on big data, like a big old struct, it’s going to make your tests run slower\! This is because CFDUMP, starting after CF 6.1, turned into a massive bloated slow pig of a tag, and debug() simply calls cfdump on whatever you’re passing into it. I think there are a few stray Thread.sleep(2000) calls in the source code somewhere that they forgot to take out.
  1. Tip: I keep debug() calls on during iterative development because I probably want to see the data. When I’m finished, it’s not uncommon for me to go comment them out so that they won’t affect performance. Do what you want. If you don’t mind a bit of a performance penalty, then don’t bother.

{tip}This is useful when the data you want to see are in your tests. But what if you want to see variables in your components under test? You can use [request.debug()|]] for that.{tip}

Using CFDUMP and CFOUTPUT in your tests

You can use cfdump and cfoutput in your tests, and the output will show up in the test output.

BIG NOTE: If your test fails, i.e. an error occurs or an assertion returns false, the output will not show up. This is why we recommend using debug().

Viewing this output in the Eclipse Plugin

In the eclipse plugin, run a test (or a single method of a single test, or multiple methods, or everything in the test tree… whatever it is you want to run) When the test completes, hit “b” on the keyboard. “b” for Browser. Or hit F8. Or right click in the test view and select Open test case results in browser This will open up a browser view with the debug() and cfoutput/cfdumps from the selected tests/methods. If your eclipse preference is set to use the internal browser by default, then this will open up Eclipse’s internal browser. If your preference is set to use an external browser, it’ll pop open a new browser window (or tab, depending on your system setup).

The output will look like this:

Viewing this output in the web browser

When you run tests using the html or extjs browser runners, you get a column at the far right that says “output” or “expand”. Just click the link and you get your stuff.

Here’s what it looks like when you click the “view output” link when using the extjs runner:

Here’s what it looks like when you click the “expand” link in the ‘normal’ html output runner:

h3. Viewing CFCATCH info when errors occur

When a test errors (for reasons other than a failed assertion), you often want to see the dump of the cfcatch struct. MXUnit automatically puts the cfcatch info into the debug dump when an error occurs. Thus, when a test errors, just hit “b” in the eclipse plugin when the test returns, or click “view output” in the browser runner, to see your cfcatch dump.

Here’s what that looks like in Eclipse: