[gparted] Add check of PipeCapture update callback (#777973)

[Curtis Gedak <gedakc src gnome org>]

commit 8b47de88728419daae4f249ec0f1e2f1c516d2ba
Author: Mike Fleetwood <mike fleetwood googlemail com>
Date:   Tue May 23 19:23:37 2017 +0100

    Add check of PipeCapture update callback (#777973)
    
    Also ensure that the PipeCapture calls registered update callbacks and
    that the data so far captured matches the leading portion of the input.
    
    Bug 777973 - Segmentation fault on bad disk

 tests/test_PipeCapture.cc |   36 +++++++++++++++++++++++++++++++++++-
 1 files changed, 35 insertions(+), 1 deletions(-)
---
diff --git a/tests/test_PipeCapture.cc b/tests/test_PipeCapture.cc
index 4e90956..49b5630 100644
--- a/tests/test_PipeCapture.cc
+++ b/tests/test_PipeCapture.cc
@@ -142,7 +142,7 @@ std::string BinaryStringToPrint( size_t offset, const char * s, size_t len )
 class PipeCaptureTest : public ::testing::Test
 {
 protected:
-       PipeCaptureTest() : eof_signalled( false )  {};
+       PipeCaptureTest() : eof_signalled( false ), update_signalled( 0U )  {};
 
        virtual void SetUp();
        virtual void TearDown();
@@ -157,11 +157,13 @@ protected:
        std::string inputstr;
        Glib::ustring capturedstr;
        bool eof_signalled;
+       unsigned update_signalled;
        int pipefds[2];
        Glib::RefPtr<Glib::MainLoop> glib_main_loop;
 
 public:
        void eof_callback()  { eof_signalled = true; };
+       void update_callback_leading_match();
 };
 
 // Further setup PipeCaptureTest fixture before running each test.  Create pipe and Glib
@@ -223,6 +225,23 @@ void PipeCaptureTest::run_writer_thread()
        glib_main_loop->run();
 }
 
+// Callback fired from CapturePipe counting calls and ensuring captured string matches
+// leading portion of input string.
+void PipeCaptureTest::update_callback_leading_match()
+{
+       update_signalled ++;
+       EXPECT_BINARYSTRINGEQ( inputstr.substr( 0, capturedstr.raw().length() ),
+                              capturedstr.raw() );
+       if ( HasFailure() )
+               // No point trying to PipeCapture the rest of the input and report
+               // hundreds of further failures in the same test, so end the currently
+               // running Glib main loop immediately.
+               // References:
+               // *   Google Test, AdvancedGuide, Propagating Fatal Failures
+               // *   Google Test, AdvancedGuide, Checking for Failures in the Current Test
+               glib_main_loop->quit();
+}
+
 TEST_F( PipeCaptureTest, EmptyPipe )
 {
        // Test capturing 0 bytes with no on EOF callback registered.
@@ -270,6 +289,21 @@ TEST_F( PipeCaptureTest, LongASCIIText )
        EXPECT_TRUE( eof_signalled );
 }
 
+TEST_F( PipeCaptureTest, LongASCIITextWithUpdate )
+{
+       // Test capturing 1 MiB of ASCII text, that registered update callback occurs and
+       // intermediate captured string is a leading match for the input string.
+       inputstr = repeat( "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_\n", 16384 );
+       PipeCapture pc( pipefds[ReaderFD], capturedstr );
+       pc.signal_eof.connect( sigc::mem_fun( *this, &PipeCaptureTest::eof_callback ) );
+       pc.signal_update.connect( sigc::mem_fun( *this, &PipeCaptureTest::update_callback_leading_match ) );
+       pc.connect_signal();
+       run_writer_thread();
+       EXPECT_BINARYSTRINGEQ( inputstr, capturedstr.raw() );
+       EXPECT_GT( update_signalled, 0U );
+       EXPECT_TRUE( eof_signalled );
+}
+
 }  // namespace GParted
 
 // Custom Google Test main() which also initialises the Glib threading system for