[ThreadPlan] Add a test for thread step-in -r, NFC (reapply)

Adds test coverage for ThreadPlanStepInRange::SetAvoidRegexp, but
disables the test on Windows.

See:
http://lab.llvm.org:8080/coverage/coverage-reports/coverage/Users/buildslave/jenkins/workspace/coverage/llvm-project/lldb/source/Target/ThreadPlanStepInRange.cpp.html#L309

Differential Revision: https://reviews.llvm.org/D91220

lldb/packages/Python/lldbsuite/test/lldbtest.py

@@ -126,6 +126,8 @@ OBJECT_PRINTED_CORRECTLY = "Object printed correctly"
 
 SOURCE_DISPLAYED_CORRECTLY = "Source code displayed correctly"
 
+STEP_IN_SUCCEEDED = "Thread step-in succeeded"
+
 STEP_OUT_SUCCEEDED = "Thread step-out succeeded"
 
 STOPPED_DUE_TO_EXC_BAD_ACCESS = "Process should be stopped due to bad access exception"

lldb/test/API/lang/c/stepping/TestThreadStepInAvoidRegexp.py

@@ -0,0 +1,34 @@
+"""
+Test thread step-in [ -r | --step-over-regexp ].
+"""
+
+
+
+import lldb
+from lldbsuite.test.lldbtest import *
+import lldbsuite.test.lldbutil as lldbutil
+
+
+class ThreadStepInAvoidRegexTestCase(TestBase):
+
+    mydir = TestBase.compute_mydir(__file__)
+
+    def setUp(self):
+        TestBase.setUp(self)
+        self.line2 = line_number('main.c', '// assignment to B2')
+
+    @skipIfWindows
+    def test_step_out_avoid_regexp(self):
+        """Exercise thread step-in -r"""
+        self.build()
+        lldbutil.run_to_source_breakpoint(self,
+                'frame select 2, thread step-out while stopped',
+                lldb.SBFileSpec('main.c'))
+
+        # Now step in, skipping the frames for 'b' and 'a'.
+        self.runCmd("thread step-in -r 'a'")
+
+        # We should be at the assignment to B2.
+        self.expect("thread backtrace", STEP_IN_SUCCEEDED,
+                    substrs=["stop reason = step in"],
+                    patterns=["frame #0.*main.c:%d" % self.line2])

lldb/test/API/lang/c/stepping/main.c

@@ -39,7 +39,7 @@ int main (int argc, char const *argv[])
 {
     int A1 = a(1); // frame select 2, thread step-out while stopped at "c(1)"
 
-    int B2 = b(2);
+    int B2 = b(2); // assignment to B2
 
     int A3 = a(3); // frame select 1, thread step-out while stopped at "c(3)"