--- a/TestResource.st Thu Oct 13 19:08:08 2016 +0200
+++ b/TestResource.st Thu Oct 13 19:08:17 2016 +0200
@@ -16,6 +16,60 @@
"
!
+!TestResource class methodsFor:'documentation'!
+
+documentation
+"
+Normally a test will set up all the objects it needs and tear them down again after it has run.
+This self-containedness makes a test more robust.
+Use TestResources only for objects that are needed by several tests and that are too 'expensive'
+(in time or otherwise) to recreate and destroy for each test.
+
+A viable approach is to develop the code in MyTestCase's #setUp and #tearDown methods,
+then at some point refactor the code into the #setUp and #tearDown of a TestResource
+whose class is added to MyTestCase class>>resource method.
+
+TestResource uses the singleton pattern.
+A TestResource class will set up a single instance of itself when first requested and tear it down again
+at the end of TestSuite>>run (or TestCase>>run, >>debug and >>debugAsFailure).
+Normally, a TestResource, once setUp, remains active during the running of all remaining tests
+and is #reset after all tests have run.
+
+For an exception, see subclass CompetingResource in SUnitResourcePatterns.
+Users can choose to #reset a resource in the #tearDown of a test that alters it,
+sacrificing the performance gain of having a single #setUp of the resource for the certainty
+that other tests using it will not see the alterations.
+
+Generally however, this should be the exception:
+if you need to reset the resource for every test that uses it,
+its code should just be part of your test's #setUp and #tearDown code.
+
+To use, create a subclass of TestResource and override the following:
+ - TestCase class>>resources, to return a collection including the TestResource class,
+ for all test case classes that need it
+ * a TestCase' resources are set up in the order returned and torn down in the reverse order
+ - TestResource class>>resources, if the resource itself always needs some other resource
+ to be present before it can set up
+ * a TestResource's resource are set up before it and torn down after it, and are set up in the order returned and torn down in the reverse order
+ - TestResource>>setUp and tearDown, to define initial and final behaviour (just like a test)
+ - TestResource>>isAvailable, to return true if it is and false if it isn't
+ (the framework calls this after setUp); ideally, this call should not change the resource' state
+ - that should be done in setUp
+
+TestResource implements the singleton pattern in its class-side #isAvailable and #reset methods.
+Do not override these when creating specific resources; unless you are developing a whole new pattern of use,
+it will always be correct to override instance-side #setUp, #tearDown and #isAvailable,
+and dangerous to override class>>isAvailable, class>>isAlreadyAvailable and class>>reset.
+
+Generally, users do not code interactions with a test's resources during the running of a test.
+Code that reads a resource' values while leaving its state strictly alone is safe enough.
+A test must leave a resource in a clean state: always use #reset if a test must protect
+later-running tests from unsafe changes (and review whether in such a case a resource
+is the right thing to use in the first place).
+
+See my superclass' comment for assertion and logging information.
+"
+! !
!TestResource class methodsFor:'instance creation'!