test that flutter_rust_bridge works

flutter_app/rust_builder/macos/rust_lib_flutter_app.podspec

@@ -0,0 +1,44 @@
+#
+# To learn more about a Podspec see http://guides.cocoapods.org/syntax/podspec.html.
+# Run `pod lib lint rust_lib_flutter_app.podspec` to validate before publishing.
+#
+Pod::Spec.new do |s|
+  s.name             = 'rust_lib_flutter_app'
+  s.version          = '0.0.1'
+  s.summary          = 'A new Flutter FFI plugin project.'
+  s.description      = <<-DESC
+A new Flutter FFI plugin project.
+                       DESC
+  s.homepage         = 'http://example.com'
+  s.license          = { :file => '../LICENSE' }
+  s.author           = { 'Your Company' => 'email@example.com' }
+
+  # This will ensure the source files in Classes/ are included in the native
+  # builds of apps using this FFI plugin. Podspec does not support relative
+  # paths, so Classes contains a forwarder C file that relatively imports
+  # `../src/*` so that the C sources can be shared among all target platforms.
+  s.source           = { :path => '.' }
+  s.source_files     = 'Classes/**/*'
+  s.dependency 'FlutterMacOS'
+
+  s.platform = :osx, '10.11'
+  s.pod_target_xcconfig = { 'DEFINES_MODULE' => 'YES' }
+  s.swift_version = '5.0'
+
+  s.script_phase = {
+    :name => 'Build Rust library',
+    # First argument is relative path to the `rust` folder, second is name of rust library
+    :script => 'sh "$PODS_TARGET_SRCROOT/../cargokit/build_pod.sh" ../../rust rust_lib_flutter_app',
+    :execution_position => :before_compile,
+    :input_files => ['${BUILT_PRODUCTS_DIR}/cargokit_phony'],
+    # Let XCode know that the static library referenced in -force_load below is
+    # created by this build step.
+    :output_files => ["${BUILT_PRODUCTS_DIR}/librust_lib_flutter_app.a"],
+  }
+  s.pod_target_xcconfig = {
+    'DEFINES_MODULE' => 'YES',
+    # Flutter.framework does not contain a i386 slice.
+    'EXCLUDED_ARCHS[sdk=iphonesimulator*]' => 'i386',
+    'OTHER_LDFLAGS' => '-force_load ${BUILT_PRODUCTS_DIR}/librust_lib_flutter_app.a',
+  }
+end