Added test for service name parsing from spans

Signed-off-by: John <dorman@overlooked.us>

internal/coreinternal/processor/filterspan/filterspan_test.go

@@ -249,6 +249,7 @@ func TestServiceNameForResource(t *testing.T) {
 	name, found := serviceNameForResource(td.ResourceSpans().At(0).Resource())
 	require.Equal(t, name, "<nil-service-name>")
 	require.False(t, found)
+
 	td = testdata.GenerateTracesOneSpan()
 	resource := td.ResourceSpans().At(0).Resource()
 	name, found = serviceNameForResource(resource)
@@ -260,3 +261,16 @@ func TestServiceNameForResource(t *testing.T) {
 	require.Equal(t, name, "test-service")
 	require.True(t, found)
 }
+
+func TestServiceNameForSpan(t *testing.T) {
+	td := testdata.GenerateTracesOneSpanNoResource()
+	span := td.ResourceSpans().At(0).InstrumentationLibrarySpans().At(0).Spans().At(0)
+	name, found := serviceNameForSpan(span)
+	require.Equal(t, name, "<nil-service-name>")
+	require.False(t, found)
+
+	span.Attributes().InsertString(conventions.AttributeServiceName, "test-service")
+	name, found = serviceNameForSpan(span)
+	require.Equal(t, name, "test-service")
+	require.True(t, found)
+}