unified: Add basic test

Author: asgerf

unified/ql/test/query-tests/unusedentities/UnusedVariable.expected

@@ -0,0 +1,2 @@
+| test.swift:2:9:2:9 | a | Unused local variable 'a' |
+| test.swift:12:9:12:9 | a | Unused local variable 'a' |

unified/ql/test/query-tests/unusedentities/UnusedVariable.qlref

@@ -0,0 +1,2 @@
+query: queries/unusedentities/UnusedVariable.ql
+postprocess: utils/test/InlineExpectationsTestQuery.ql

unified/ql/test/query-tests/unusedentities/test.swift

@@ -0,0 +1,18 @@
+func t1() -> Int {
+    let a = 1 // $ Alert[unified/unused-variable]
+    let b = 2
+    return b
+}
+
+func t2() -> Int {
+    func foo(callback: (Int) -> Void) -> String {
+        callback()
+        return "df"
+    }
+    // Note: This currently fails because the trailing closure is not extracted correctly
+    let a = 1 // $ SPURIOUS: Alert
+    print(foo() { _ in
+        print(a)
+        let b = 2 // $ MISSING: Alert[unified/unused-variable]
+    })
+}