Migrate contents of SwiftBuildTest to Firestore_SwiftTests_iOS (#1524)

* Move main.swift to BasicCompileTests.swift

* Remove SwiftBuildTest from the Podfile, Xcode project, build.sh

Add Firestore_SwiftTests_iOS, but only if building with Xcode 9 or
better.

1 files changed, 14 insertions, 6 deletions

diff --git a/scripts/build.sh b/scripts/build.sh
index ce3e58e..6ae512f 100755
--- a/scripts/build.sh
+++ b/scripts/build.sh
@@ -121,6 +121,10 @@ cmake_options=(
   --warn-uninitialized
 )
 
+xcode_version=$(xcodebuild -version | head -n 1)
+xcode_version="${xcode_version/Xcode /}"
+xcode_major="${xcode_version/.*/}"
+
 if [[ -n "${SANITIZERS:-}" ]]; then
   for sanitizer in $SANITIZERS; do
     case "$sanitizer" in
@@ -216,15 +220,19 @@ case "$product-$method-$platform" in
         build \
         test
 
-    RunXcodebuild \
-        -workspace 'Firestore/Example/Firestore.xcworkspace' \
-        -scheme "Firestore_IntegrationTests_$platform" \
-        "${xcb_flags[@]}" \
-        build
+    # Firestore_SwiftTests_iOS require Swift 4, which needs Xcode 9
+    if [[ "$xcode_major" -ge 9 ]]; then
+      RunXcodebuild \
+          -workspace 'Firestore/Example/Firestore.xcworkspace' \
+          -scheme "Firestore_SwiftTests_$platform" \
+          "${xcb_flags[@]}" \
+          build \
+          test
+    fi
 
     RunXcodebuild \
         -workspace 'Firestore/Example/Firestore.xcworkspace' \
-        -scheme 'SwiftBuildTest' \
+        -scheme "Firestore_IntegrationTests_$platform" \
         "${xcb_flags[@]}" \
         build
     ;;