Fix: replicate gst_sample_get_buffer{,list} returns NULL semantic

go.mod

@@ -4,5 +4,6 @@ go 1.16
 
 require (
 	github.com/mattn/go-pointer v0.0.1
+	github.com/stretchr/testify v1.8.0
 	github.com/tinyzimmer/go-glib v0.0.25
 )

go.sum

@@ -1,4 +1,19 @@
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/mattn/go-pointer v0.0.1 h1:n+XhsuGeVO6MEAp7xyEukFINEa+Quek5psIR/ylA6o0=
 github.com/mattn/go-pointer v0.0.1/go.mod h1:2zXcozF6qYGgmsG+SeTZz3oAbFLdD3OWqnUbNvJZAlc=
-github.com/tinyzimmer/go-glib v0.0.24 h1:ktZZC22/9t88kGRgNEFV/SESgIWhGHE+q7Z7Qj++luw=
-github.com/tinyzimmer/go-glib v0.0.24/go.mod h1:ltV0gO6xNFzZhsIRbFXv8RTq9NGoNT2dmAER4YmZfaM=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.8.0 h1:pSgiaMZlXftHpm5L7V1+rVB+AZJydKsMxsQBIJw4PKk=
+github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
+github.com/tinyzimmer/go-glib v0.0.25 h1:2GpumtkxA0wpXhCXP6D3ksb5pGMfo9WbhgLvEw8njK4=
+github.com/tinyzimmer/go-glib v0.0.25/go.mod h1:ltV0gO6xNFzZhsIRbFXv8RTq9NGoNT2dmAER4YmZfaM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

gst/gst_sample.go

@@ -1,6 +1,9 @@
 package gst
 
 // #include "gst.go.h"
+// GstSample* new_empty_sample() {
+//   return gst_sample_new(NULL, NULL, NULL, NULL);
+// }
 import "C"
 
 import (
@@ -30,6 +33,12 @@ func FromGstSampleUnsafeFull(sample unsafe.Pointer) *Sample {
 	return s
 }
 
+// NewEmptySample creates an empty GstSample.
+// This is meant for test usage only.  Tests in Go are not permitted to use CGO directly
+func NewEmptySample() *Sample {
+	return FromGstSampleUnsafeFull(unsafe.Pointer(C.new_empty_sample()))
+}
+
 // Instance returns the underlying *GstSample instance.
 func (s *Sample) Instance() *C.GstSample { return C.toGstSample(unsafe.Pointer(s.sample)) }
 
@@ -46,12 +55,18 @@ func (s *Sample) Copy() *Sample {
 
 // GetBuffer returns the buffer inside this sample.
 func (s *Sample) GetBuffer() *Buffer {
-	return FromGstBufferUnsafeNone(unsafe.Pointer(C.gst_sample_get_buffer((*C.GstSample)(s.Instance()))))
+	if p := unsafe.Pointer(C.gst_sample_get_buffer((*C.GstSample)(s.Instance()))); p != C.NULL {
+		return FromGstBufferUnsafeNone(p)
+	}
+	return nil
 }
 
 // GetBufferList gets the buffer list associated with this sample.
 func (s *Sample) GetBufferList() *BufferList {
-	return FromGstBufferListUnsafeNone(unsafe.Pointer(C.gst_sample_get_buffer_list(s.Instance())))
+	if p := unsafe.Pointer(C.gst_sample_get_buffer_list(s.Instance())); p != C.NULL {
+		return FromGstBufferListUnsafeNone(p)
+	}
+	return nil
 }
 
 // GetCaps returns the caps associated with this sample. Take a ref if you need to hold on to them

gst/gst_segment_test.go

@@ -0,0 +1,51 @@
+package gst_test
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/tinyzimmer/go-gst/gst"
+)
+
+func TestSampleReturnsValidBuffer(t *testing.T) {
+	sut := gst.NewEmptySample()
+
+	buf1 := gst.NewEmptyBuffer()
+	sut.SetBuffer(buf1)
+
+	// We cannot expect equivalance between Go Buffer wrapper
+	// and the one returned, however .Instance should match
+	buf2 := sut.GetBuffer()
+	assert.NotNil(t, buf2)
+	assert.Equal(t, buf1.Instance(), buf2.Instance())
+}
+
+func TestSampleReturnsNilBuffer(t *testing.T) {
+	sut := gst.NewEmptySample()
+	assert.Nil(t, sut.GetBuffer())
+}
+
+func TestSampleReturnsValidBufferList(t *testing.T) {
+	sut := gst.NewEmptySample()
+
+	bufList1 := gst.NewBufferList(nil)
+	sut.SetBufferList(bufList1)
+
+	// We cannot expect equivalance between Go Buffer wrapper
+	// and the one returned, however .Instance should match
+	bufList2 := sut.GetBufferList()
+	assert.NotNil(t, bufList2)
+	assert.Equal(t, bufList1.Instance(), bufList2.Instance())
+}
+
+func TestSampleReturnsNilBufferList(t *testing.T) {
+	sut := gst.NewEmptySample()
+	assert.Nil(t, sut.GetBufferList())
+}
+
+func TestMain(m *testing.M) {
+	gst.Init(nil)
+	defer gst.Deinit()
+	os.Exit(m.Run())
+}