JS. First execution branch in `Recursion.factorial(n)` is not covered

[alisevych]

Description

Generated tests for samples\commonRecursion.js doesn't cover line 4 (n < 0 branch).

To Reproduce

1. Install the latest IU plugin built from unit-test-bot/rc3102023 branch in IntelliJ Idea Ultimate 2022.3.2
   take utbot-intellij-IU-2023.3.* artefact
2. Create/open a JavaScript project
3. Copy samples folder from utbot-js module and paste it into this project
4. Generate tests for Recursion.factorial(n) function in samples/commonRecursion.js
5. Check the generated tests

Expected behavior

There should be a test for every execution branch.
Or at least UnitTestBot should try to cover all lines during timeout.

Actual behavior

4-th line with condition (n < 0) is not covered with tests.
There are only 2 tests generated stably: for (n==0) and (n > 0).
Test generation finishes before timeout is reached.

Visual proofs (screenshots, logs, images)

const fileUnderTest = require("./../samples/commonRecursion.js")
const assert = require("assert")

///region Test suites for executable Recursion.factorial


it("testFactorial1", function ()
 {
    let recursion = new fileUnderTest.Recursion()
    
    let actual = recursion.factorial(0.0)
    
    assert.deepEqual(1, actual)
}
)

it("testFactorial2", function ()
 {
    let recursion = new fileUnderTest.Recursion()
    
    let actual = recursion.factorial(1.1125370618783376E-308)
    
    assert.deepEqual(-1.1125370618783376E-308, actual)
}
)

///endregion

Environment

Windows 10 Po
IntelliJ IDEA Ultimate 2022.3.2
Node.js 18.14.2

Additional context

Tried with the same result:

• Base / Fast mode
• Timeout 10/60 sec

[alisevych]

Reproducing

on fresh version of unit-test-bot/rc3102023 branch. IU-plugin from this run:
https://github.com/UnitTestBot/UTBotJava/actions/runs/4434721564
The last commit for this run was dccfdad.

There is one more test with String input.
But a test with a number < 0 is not generated.

[rudolf101]

On the above run, one of the generated tests looks like this:

it("testFactorial3", function ()
 {
    let recursion = new fileUnderTest.Recursion()
    
    let actual = recursion.factorial("\n\n")
    
    assert.deepEqual(0, actual)
}
)

Fun fact, this test is covering the first brunch (n<0) like this:
factorial("\n\n") -> return "\n\n" * factorial("\n\n" - 1) -> return "\n\n" * -1 -> 0
factorial("\n\n" - 1) -> factorial(-1) -> -1

JavaScript is weird

[alisevych]

So, this bug was fixed after this PR was cherry-picked into release branch:

• Improve fuzzer & test exports/imports in JavaScript module #1909