Enhance testing utilities

[cescoffier]

Fix #465

The PR adds:

in UniAssertSubscriber:

• awaitItem - with and without duration
• awaitFailure- with and without duration and validation of the failure
• awaitSubscription - with or without duration

in AssertSubscriber:

• awaitCompletion - with and without duration
• awaitFailure- with and without duration and validation of the failure
• awaitNextItems and awaitNextItem
• awaitSubscription - with or without duration
• assertLastItem and getLastItem

[jponge]

Oh there's an issue in MultiGroupTest.testGroupByWithUpstreamFailure

[cescoffier]

It means the assertions are working :-)

More seriously, there is a race. When the source started to emit items, you can't really awaitNextItems as it may have already received some.

We may need to introduce another assertion, awaiting for a total number of items is received (but should it be strict or anything greater would be ok).

[codecov]

Codecov Report

Merging #494 (d2045da) into main (f8bb371) will increase coverage by 0.16%.
The diff coverage is 87.08%.

@@             Coverage Diff              @@
##               main     #494      +/-   ##
============================================
+ Coverage     89.95%   90.11%   +0.16%     
- Complexity     2931     3005      +74     
============================================
  Files           382      382              
  Lines         11340    11577     +237     
  Branches       1420     1446      +26     
============================================
+ Hits          10201    10433     +232     
- Misses          578      581       +3     
- Partials        561      563       +2     

Impacted Files	Coverage Δ	Complexity Δ
...e/mutiny/helpers/spies/MultiOnCancellationSpy.java	69.23% <33.33%> (-30.77%)	6.00 <2.00> (+2.00)	⬇️
.../smallrye/mutiny/helpers/test/AssertionHelper.java	73.39% <42.85%> (-4.16%)	48.00 <2.00> (+3.00)	⬇️
...n/java/io/smallrye/mutiny/groups/UniOnFailure.java	91.89% <50.00%> (-8.11%)	25.00 <1.00> (-1.00)
...llrye/mutiny/helpers/test/UniAssertSubscriber.java	91.85% <87.83%> (-5.83%)	54.00 <27.00> (+17.00)	⬇️
...smallrye/mutiny/helpers/test/AssertSubscriber.java	93.90% <93.06%> (-3.54%)	73.00 <48.00> (+43.00)	⬇️
...tiny/operators/uni/builders/DefaultUniEmitter.java	93.10% <0.00%> (-6.90%)	12.00% <0.00%> (-1.00%)
...mallrye/mutiny/helpers/queues/MpscLinkedQueue.java	90.32% <0.00%> (-6.46%)	27.00% <0.00%> (-1.00%)
...erators/multi/builders/SerializedMultiEmitter.java	81.01% <0.00%> (-1.27%)	25.00% <0.00%> (-1.00%)
...smallrye/mutiny/operators/multi/MultiBufferOp.java	88.70% <0.00%> (-0.81%)	5.00% <0.00%> (ø%)
... and 11 more

[jponge]

See typo, otherwise a great PR!