ktesting: doc updates and fixes

First-in-first-out is wrong for cleanup, it's LIFO.

Updated some comments to make them more informative and fixed indention.

test/utils/ktesting/assert.go

@@ -119,7 +119,8 @@ func buildDescription(explain ...interface{}) string {
 //
 //	cb := func(func(tCtx ktesting.TContext) int {
 //	    value, err := doSomething(...)
-//	   ktesting.ExpectNoError(tCtx, err, "something failed")
+//	    tCtx.ExpectNoError(err, "something failed")
+//	    assert(tCtx, 42, value, "the answer")
 //	    return value
 //	}
 //	tCtx.Eventually(cb).Should(gomega.Equal(42), "should be the answer to everything")
@@ -145,7 +146,16 @@ func buildDescription(explain ...interface{}) string {
 //	cb := func(func(tCtx ktesting.TContext) int {
 //	    value, err := doSomething(...)
 //	    if errors.Is(err, SomeFinalErr) {
-//	    gomega.StopTrying("permanent failure).Wrap(err).Now()
+//	        // This message completely replaces the normal
+//	        // failure message and thus should include all
+//	        // relevant information.
+//	        //
+//	        // github.com/onsi/gomega/format is a good way
+//	        // to format arbitrary data. It uses indention
+//	        // and falls back to YAML for Kubernetes API
+//	        // structs for readability.
+//	        gomega.StopTrying("permanent failure, last value:\n%s", format.Object(value, 1 /* indent one level */)).
+//	            Wrap(err).Now()
 //	    }
 //	    ktesting.ExpectNoError(tCtx, err, "something failed")
 //	    return value

test/utils/ktesting/tcontext.go

@@ -83,7 +83,7 @@ type TContext interface {
 	Cancel(cause string)
 
 	// Cleanup registers a callback that will get invoked when the test
-	// has finished. Callbacks get invoked in first-in-first-out order.
+	// has finished. Callbacks get invoked in last-in-first-out order (LIFO).
 	//
 	// Beware of context cancellation. The following cleanup code
 	// will use a canceled context, which is not desirable: