early boot the simulator to avoid false travis failures

Tests were frequently failing, especially during peak travis-ci hours.

Also, saved some time by removing redundant build from test script.

// FREEBIE

.travis.yml

@@ -3,6 +3,9 @@ cache: cocoapods # pod install somtimes takes >20 minutes, so lets cache this
 
 osx_image: xcode8
 
+env:
+  -EARLY_START_SIMULATOR=1 # early starting simulator reduces false negatives due to test timeouts
+
 before_install:
     - brew update # we may not be running the latest version so always update
     - brew outdated xctool || brew upgrade xctool # only upgrade if outdated (saves 2 minutes)

Makefile

@@ -1,7 +1,9 @@
 # Make sure we're failing even though we pipe to xcpretty
 SHELL=/bin/bash -o pipefail -o errexit
 
-BUILD_DESTINATION = platform=iOS Simulator,name=iPhone 6,OS=9.3
+# iPhone6, iOS10
+DEVICE_UUID:=$(shell xcrun instruments -s | grep -o "iPhone 6 (10.0) \[.*\]" | grep -o "\[.*\]" | sed "s/^\[\(.*\)\]$$/\1/")
+BUILD_DESTINATION = platform=iOS Simulator,id=${DEVICE_UUID}
 WORKING_DIR = ./
 SCHEME = Signal
 XCODE_BUILD = xcrun xcodebuild -workspace $(SCHEME).xcworkspace -scheme $(SCHEME) -sdk iphonesimulator
@@ -20,14 +22,22 @@ build: pod_install
 	cd $(WORKING_DIR) && \
 		$(XCODE_BUILD) build | xcpretty
 
-retest:
+retest: optional_early_start_simulator
 	cd $(WORKING_DIR) && \
 		$(XCODE_BUILD) \
 			-destination '${BUILD_DESTINATION}' \
-			build test | xcpretty
+			test | xcpretty
 
 clean:
 	cd $(WORKING_DIR) && \
 		$(XCODE_BUILD) \
 			clean | xcpretty
 
+optional_early_start_simulator:
+ifdef EARLY_START_SIMULATOR
+		echo "Waiting for simulator to start to help with testing timeouts" &&\
+		xcrun instruments -w '${DEVICE_UUID}' || true # xcrun can return irrelevant non-zeroes.
+else
+		echo "Not waiting for simulator."
+endif
+