Multiple "Beginning test session". Build takes 1 hour +

Build Environment Mobile
,
1

Hi,
on my recent branch, I see that my commits initiate multiple simulators for the test phase.
the tests fail for some reason while locally and on another branch works.
suspicious output :

▸ Touching MyAppSwiftTests.xctest
▸ Signing /Users/distiller/Library/Developer/Xcode/DerivedData/MyApp-ehdschoxvihfoxhjhdxmzroeowfh/Build/Products/Debug-iphonesimulator/MyApp.app/PlugIns/MyAppSwiftTests.xctest
2017-12-26 00:43:28.175 xcodebuild[1180:24295]  IDETestOperationsObserverDebug: Writing diagnostic log for test session to:
/var/folders/ms/xg67k5sn16xc7sdr_w3q45840000gn/T/com.apple.dt.XCTest/IDETestRunSession-C347A801-E43E-47AB-A7C2-C14E0AD15621/MyAppLogicTests-76B5D71D-81BA-410D-A365-E95DD245F527/Session-MyAppLogicTests-2017-12-26_004328-eyNIpr.log
2017-12-26 00:43:28.175 xcodebuild[1180:8040] [MT] IDETestOperationsObserverDebug: (A85350EB-97E4-4817-AFDB-8E519B23F179) Beginning test session MyAppLogicTests-A85350EB-97E4-4817-AFDB-8E519B23F179 at 2017-12-26 00:43:28.176 with Xcode 9B55 on target <DVTiPhoneSimulator: 0x7ffc2bd94470> {
		SimDevice: iPhone 7 (52CC79E9-843D-4A98-85EE-08776F78783A, iOS 11.1, Booted)
} (11.1 (15B87))
2017-12-26 00:43:36.408 xcodebuild[1180:21695]  IDETestOperationsObserverDebug: Writing diagnostic log for test session to:
/var/folders/ms/xg67k5sn16xc7sdr_w3q45840000gn/T/com.apple.dt.XCTest/IDETestRunSession-C347A801-E43E-47AB-A7C2-C14E0AD15621/MyAppLogicTests-76B5D71D-81BA-410D-A365-E95DD245F527/Session-MyAppLogicTests-2017-12-26_004336-e3iuBe.log
2017-12-26 00:43:36.408 xcodebuild[1180:8040] [MT] IDETestOperationsObserverDebug: (04467F0E-3563-4203-A7E9-F32868FD9D70) Beginning test session MyAppLogicTests-04467F0E-3563-4203-A7E9-F32868FD9D70 at 2017-12-26 00:43:36.408 with Xcode 9B55 on target <DVTiPhoneSimulator: 0x7ffc2bd94470> {
		SimDevice: iPhone 7 (52CC79E9-843D-4A98-85EE-08776F78783A, iOS 11.1, Booted)
} (11.1 (15B87))
there are more than 200  IDETestOperationsObserverDebug messages like those.

cicle.yml:

set -o pipefail &&
      xcodebuild
        CODE_SIGNING_REQUIRED=NO
        CODE_SIGN_IDENTITY=
        PROVISIONING_PROFILE=
        -destination 'platform=iOS Simulator,OS=11.1,name=iPhone 7'
        -workspace MyApp.xcworkspace
        -scheme "MyApp"
        -enableCodeCoverage YES
        clean build test |
      tee $CIRCLE_ARTIFACTS/xcode_raw.log |
      xcpretty --color --report junit --output $CIRCLE_TEST_REPORTS/xcode/results.xml

Thanks in advance,
Idoz