render exceptions in conditions as condition failure

[Fuud]

Idea

Spock has the best exception rendering I have ever see. For example, lets take a spec:

    def "responce code should starts with 200"(){
        when:
        def map = new HashMap<String, String>()
        map.put("responceCode", "404 NOT FOUND")
        then:
        map.get("responceCode").startsWith("200")
    }

It fails and has good rendering:

Condition not satisfied:

map.get("responceCode").startsWith("200")
|   |                   |
|   404 NOT FOUND       false
[responceCode:404 NOT FOUND]

    at org.spockframework.guice.JavaStubs.responce code should starts with 200(JavaStubs.groovy:98)

But how it will be rendered if map miss value for key "responceCode"? For example in this spec:

    def "responce code should starts with 200"(){
        when:
        def map = new HashMap<String, String>()
        map.put("ResponceCode", "404 NOT FOUND")
        then:
        map.get("responceCode").startsWith("200")
    }

just an exception:

java.lang.NullPointerException: Cannot invoke method startsWith() on null object
    at Test.responce code should starts with 200(Test.groovy:8)

we can understand that map does not contains entry for "responceCode" but we can not inspect what map really contains.

With my modifications it will become more friendly:

Condition not satisfied:

map.get("responceCode").startsWith("200")
|   |                   |
|   null                java.lang.NullPointerException: Cannot invoke method startsWith() on null object
[ResponceCode:404 NOT FOUND]

    at org.spockframework.guice.Test.responce code should starts with 200(Test.groovy:11)
Caused by: java.lang.NullPointerException: Cannot invoke method startsWith() on null object
    ... 1 more

So exceptions that occured during evaluating condition become part of rendering.

Implementation

Lets take for example this condition:

map.get("key") == "abc"

Before my changes it will be transformed to (I omit unnecessary parts)

SpockRuntime.verifyCondition(
                valueRecorder.reset(),
                "map.get(\"key\") == \"abc\"",
                8,
                9,
                null,
                valueRecorder.record(
                        6,
                        Boolean.valueOf(
                                ScriptBytecodeAdapter.compareEqual(
                                        valueRecorder.record(4,
                                                ScriptBytecodeAdapter.invokeMethodN(
                                                        Test.class,
                                                        valueRecorder.record(0, map),
                                                        (String)valueRecorder.record(1, "get"),
                                                        [valueRecorder.record(2, "key") ]
                                                )
                                        ),
                                        valueRecorder.record(5, "abc")
                                )
                        )
                )
        );

We need to:

1. handle exception, so surround this expression with try-catch.
2. to understand number of value that was not recorded because of exception, so lets remember value number before recording value (and before evaluating expression for this value).

try {
    SpockRuntime.verifyCondition(
            $spock_valueRecorder.reset(), 
            "map.get(\"key\") == \"abc\"", 
            14,
            7,
            null,
            $spock_valueRecorder.record(
                    $spock_valueRecorder.startRecordingValue(6),
                    Boolean.valueOf(
                            ScriptBytecodeAdapter.compareEqual(
                                    $spock_valueRecorder.record(
                                            $spock_valueRecorder.startRecordingValue(4),
                                            ScriptBytecodeAdapter.invokeMethodN(
                                                    ExceptionsInConditionsSpec.class,
                                                    $spock_valueRecorder.record(
                                                            $spock_valueRecorder.startRecordingValue(0),
                                                            map
                                                    ),
                                                    (String) ShortTypeHandling.castToString(
                                                            $spock_valueRecorder.record(
                                                                    $spock_valueRecorder.startRecordingValue(1),
                                                                    "get")
                                                    ),
                                                    [$spock_valueRecorder.record(
                                                            $spock_valueRecorder.startRecordingValue(2),
                                                            "key"
                                                    )]
                                            )
                                    ),
                                    $spock_valueRecorder.record(
                                            $spock_valueRecorder.startRecordingValue(5),
                                            "abc")
                            )
                    )
            )
    );
}
catch (Throwable throwable) {
    SpockRuntime.conditionFailedWithException($spock_valueRecorder, "map.get(\"key\") == \"abc\"", 14, 7, null, throwable);
}

ValueRecorder,startRecording method:

  private final Stack<Integer> startedRecordings = new Stack<Integer>();

  public int startRecordingValue(int index){
    startedRecordings.push(index);
    return index;
  }

So we add value number to stack before evaluating expression for this value. And remove value number from top of stack when value is written to ValueRecording. And when exception is thrown we can learn where exception is thrown by peeking value from top of stack.

[pniederw]

Thanks a lot for your pull request. I like the idea, and will review over the weekend.

[Fuud]

@pniederw any review?

[jbaruch]

👍

[pniederw]

I've started work on this pull request, and should have it integrated soon. Thanks for your patience.

[PascalSchumacher]

very nice enhancement 👍

[Fuud]

@pniederw Any progress?

[leonard84]

👍

[Fuud]

@pniederw Any progress?

[jirutka]

👍

[stavytskyi]

👍

[Fuud]

@pniederw Why this pull request was not merged yet? Is anything wrong with code?

[PascalSchumacher]

@robfletcher Maybe you can have a look a this pull request (as a spock user this seems like a very nice feature)?

[robfletcher]

Yeah, this looks excellent. I'm going to merge it if I don't hear a good reason why I shouldn't in the next few hours.

[Fuud]

@robfletcher Did you found "good reason" not to merge?

[Fuud]

Open Question: What to do with invocation of void methods and assignments? Should such constructions became conditions because them can throw an exception.

[PascalSchumacher]

Maybe this can be merged before the next release?

[szpak]

Yeah, this looks excellent. I'm going to merge it if I don't hear a good reason why I shouldn't in the next few hours.

@robfletcher Time flies. Any chance to get it merged in the foreseeable future?

[dpost]

any update on this?

[robfletcher]

Superseded by #549 which is now merged