add test by @nathawes

Author: kastiglione

test/Index/Store/driver-ignore-system-modules.swift

@@ -0,0 +1,35 @@
+// RUN: %empty-directory(%t)
+
+// Make a basic clang framework to import
+//
+// RUN: %empty-directory(%t/MySystemFramework.framework/Headers)
+// RUN: %empty-directory(%t/MySystemFramework.framework/Modules)
+// RUN: echo 'void someSystemFunc(int arg);' > %t/MySystemFramework.framework/Headers/MySystemFramework.h
+// RUN: echo 'framework module MySystemFramework { umbrella header "MySystemFramework.h" export * }' > %t/MySystemFramework.framework/Modules/module.modulemap
+
+import MySystemFramework
+someSystemFunc(2)
+
+// Index this file with and without ignoring system frameworks
+//
+// RUN: %target-swiftc_driver -index-store-path %t/idx1 -o %t/file.o -Fsystem %t -typecheck %s
+// RUN: %target-swiftc_driver -index-store-path %t/idx2 -o %t/file.o -index-ignore-system-modules -Fsystem %t -typecheck %s
+// RUN: c-index-test core -print-unit %t/idx1 | %FileCheck --check-prefixes=ALLOWSYSTEM,BOTH %s
+// RUN: c-index-test core -print-unit %t/idx2 | %FileCheck --check-prefixes=IGNORESYSTEM,BOTH %s
+
+// We should always get a dependency on the system framework in the unit for this file's module.
+//
+// BOTH: DEPEND START
+// BOTH: Unit | system | MySystemFramework |
+// BOTH: DEPEND END
+
+// We should get a unit for the system framework if not ignoring them.
+//
+// ALLOWSYSTEM: provider: clang
+// ALLOWSYSTEM-NEXT: is-system: 1
+// ALLOWSYSTEM-NEXT: is-module: 1
+// ALLOWSYSTEM-NEXT: module-name: MySystemFramework
+
+// But shouldn't if we are.
+//
+// IGNORESYSTEM-NOT: module-name: MySystemFramework