When clojure.contrib.test-is/run-tests is given an invalid argument, it
throws a NullPointerException:
user=> (use 'clojure.contrib.test-is)
nil
user=> (run-tests 'asdf)
java.lang.RuntimeException: java.lang.NullPointerException
(NO_SOURCE_FILE:0)
The issue seems harmless in a simple case like this, but in a more
complex case the error is quite hard to debug for two reasons:
- When the stack trace is longer it's not immediately obvious what
caused the NullPointerException.
- The error can be caused by a simple typo so it's quite easy to miss
when reading the code because the code "reads aloud" correctly.
Having something like 'clojure.contrib.test-is.NamespaceException: No
such namespace "asdf"' would make the source of the error easy to find.
I found this bug by having a namespace called "errorr" (deliberate
typo), and accidentally spelled it correctly as "error" in the argument
to run-tests. You might say that I got what I deserved for picking a
clever Web2.0 name like that (and I would agree :), but keep in mind
that any other typo would have worked and could have been as hard to find.
As an example, here's the the stack trace that one typo gave me.
Exception in thread "main" java.lang.RuntimeException:
java.lang.NullPointerException (run-tests.clj:0)
at clojure.lang.Compiler.eval(Compiler.java:4543)
at clojure.lang.Compiler.load(Compiler.java:4857)
at clojure.lang.Compiler.loadFile(Compiler.java:4824)
at clojure.main$load_script__5833.invoke(main.clj:206)
at clojure.main$script_opt__5864.invoke(main.clj:258)
at clojure.main$main__5888.doInvoke(main.clj:333)
at clojure.lang.RestFn.invoke(RestFn.java:413)
at clojure.lang.Var.invoke(Var.java:346)
at clojure.lang.AFn.applyToHelper(AFn.java:173)
at clojure.lang.Var.applyTo(Var.java:463)
at clojure.main.main(main.java:39)
Caused by: java.lang.RuntimeException: java.lang.NullPointerException
at clojure.lang.LazySeq.seq(LazySeq.java:46)
at clojure.lang.RT.seq(RT.java:436)
at clojure.core$seq__3133.invoke(core.clj:103)
at clojure.core$spread__3240.invoke(core.clj:383)
at clojure.core$spread__3240.invoke(core.clj:384)
at clojure.core$apply__3243.doInvoke(core.clj:390)
at clojure.lang.RestFn.invoke(RestFn.java:443)
at clojure.contrib.test_is$run_tests__4789.doInvoke(test_is.clj:914)
at clojure.lang.RestFn.invoke(RestFn.java:413)
at errorr.engine.gfx.tests$run__7.invoke(tests.clj:5)
at user$eval__10.invoke(run-tests.clj:2)
at clojure.lang.Compiler.eval(Compiler.java:4532)
... 10 more
Caused by: java.lang.NullPointerException
at
java.util.concurrent.ConcurrentHashMap.get(ConcurrentHashMap.java:768)
at clojure.lang.Namespace.find(Namespace.java:129)
at clojure.core$find_ns__4309.invoke(core.clj:2347)
at clojure.core$the_ns__4321.invoke(core.clj:2371)
at clojure.core$ns_name__4325.invoke(core.clj:2376)
at clojure.contrib.test_is$fn__4660.invoke(test_is.clj:586)
at clojure.lang.MultiFn.invoke(MultiFn.java:157)
at clojure.contrib.test_is$test_ns__4785.invoke(test_is.clj:896)
at clojure.core$map__3815$fn__3817.invoke(core.clj:1503)
at clojure.lang.LazySeq.seq(LazySeq.java:41)
... 21 more
--
Timo
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