[lldb] Add test for stepping through conformance methods

Author: felipepiovezan

lldb/test/API/lang/swift/protocols/stepping_through_witness/Makefile

@@ -0,0 +1,2 @@
+SWIFT_SOURCES := main.swift
+include Makefile.rules

lldb/test/API/lang/swift/protocols/stepping_through_witness/TestSwiftSteppingThroughWitness.py

@@ -0,0 +1,50 @@
+import lldb
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.decorators import *
+import lldbsuite.test.lldbutil as lldbutil
+
+
+@skipIf(oslist=["windows", "linux"])
+class TestSwiftSteppingThroughWitness(TestBase):
+    @swiftTest
+    def test_step_in_and_out(self):
+        """Test that stepping in and out of protocol methods work"""
+        self.build()
+        _, _, thread, _ = lldbutil.run_to_source_breakpoint(
+            self, "break here", lldb.SBFileSpec("main.swift")
+        )
+
+        thread.StepInto()
+        stop_reason = thread.GetStopReason()
+        self.assertStopReason(stop_reason, lldb.eStopReasonPlanComplete)
+
+        frame0 = thread.frames[0]
+        frame1 = thread.frames[1]
+        self.assertIn("SlowRandomNumberGenerator.random", frame0.GetFunctionName())
+        self.assertIn(
+            "protocol witness for a.RandomNumberGenerator.random",
+            frame1.GetFunctionName(),
+        )
+
+        thread.StepOut()
+        stop_reason = thread.GetStopReason()
+        self.assertStopReason(stop_reason, lldb.eStopReasonPlanComplete)
+        frame0 = thread.frames[0]
+        self.assertIn("doMath", frame0.GetFunctionName())
+
+    @swiftTest
+    def test_step_over(self):
+        """Test that stepping over protocol methods work"""
+        self.build()
+        _, _, thread, _ = lldbutil.run_to_source_breakpoint(
+            self, "break here", lldb.SBFileSpec("main.swift")
+        )
+
+        thread.StepOver()
+        stop_reason = thread.GetStopReason()
+        self.assertStopReason(stop_reason, lldb.eStopReasonPlanComplete)
+        frame0 = thread.frames[0]
+        self.assertIn("doMath", frame0.GetFunctionName())
+
+        line_entry = frame0.GetLineEntry()
+        self.assertEqual(14, line_entry.GetLine())

lldb/test/API/lang/swift/protocols/stepping_through_witness/main.swift

@@ -0,0 +1,18 @@
+protocol RandomNumberGenerator {
+    func random(in range: ClosedRange<Int>) async -> Int
+}
+
+class SlowRandomNumberGenerator: RandomNumberGenerator {
+    func random(in range: ClosedRange<Int>) async -> Int {
+        try? await Task.sleep(for: .milliseconds(500))
+        return Int.random(in: range)
+    }
+}
+
+func doMath<RNG: RandomNumberGenerator>(with rng: RNG) async {
+    let y = await rng.random(in: 101...200) // break here
+    print("Y is \(y)")
+}
+
+let rng = SlowRandomNumberGenerator()
+await doMath(with: rng)