Swift: Create library test cases for REDOS vulnerable regexs.

swift/ql/test/library-tests/regex/redos_variants.swift

@@ -0,0 +1,50 @@
+
+// --- stubs ---
+
+struct URL {
+	init?(string: String) {}
+}
+
+struct AnyRegexOutput {
+}
+
+protocol RegexComponent {
+}
+
+struct Regex<Output> : RegexComponent {
+	struct Match {
+	}
+
+	init(_ pattern: String) throws where Output == AnyRegexOutput { }
+
+	func firstMatch(in string: String) throws -> Regex<Output>.Match? { return nil}
+
+	typealias RegexOutput = Output
+}
+
+extension String {
+	init(contentsOf: URL) {
+        let data = ""
+        self.init(data)
+    }
+}
+
+// --- tests ---
+
+func myRegexpVariantsTests(myUrl: URL) throws {
+	let tainted = String(contentsOf: myUrl) // tainted
+	let untainted = "abcdef"
+
+	_ = try Regex(".*").firstMatch(in: tainted) // $ regex="call to Regex<AnyRegexOutput>.init(_:)" input=tainted
+
+	_ = try Regex("a*b").firstMatch(in: tainted) // $ regex="call to Regex<AnyRegexOutput>.init(_:)" input=tainted
+	_ = try Regex("(a*)b").firstMatch(in: tainted) // $ regex="call to Regex<AnyRegexOutput>.init(_:)" input=tainted
+	_ = try Regex("(a)*b").firstMatch(in: tainted) // $ regex="call to Regex<AnyRegexOutput>.init(_:)" input=tainted
+	_ = try Regex("(a*)*b").firstMatch(in: tainted) // $ regex="call to Regex<AnyRegexOutput>.init(_:)" input=tainted MISSING: redos-vulnerable=
+	_ = try Regex("((a*)*b)").firstMatch(in: tainted) // $ regex="call to Regex<AnyRegexOutput>.init(_:)" input=tainted MISSING: redos-vulnerable=
+
+	_ = try Regex("(a|aa?)b").firstMatch(in: tainted) // $ regex="call to Regex<AnyRegexOutput>.init(_:)" input=tainted
+	_ = try Regex("(a|aa?)*b").firstMatch(in: tainted) // $ regex="call to Regex<AnyRegexOutput>.init(_:)" input=tainted MISSING: redos-vulnerable=
+
+	// TODO: test more variant expressions.
+}