Answer

 These test tubes are made from borosilicate 3.3, so they can withstand direct heating with a Bunsen burner.
 However, please be aware that continuous intensive heating of just one area of a test tube, beaker etc. may result in softening and deformation of the glass, regardless of the glass type or brand.
 It is important to keep a test tube moving slightly within a flame, to distribute the heat more evenly and prevent the build-up of hot spots which could deform the glass. Likewise, it is always good practice to bring any glassware up to temperature fairly gradually in a heat source, to avoid the possibility of thermal shock and cracking.

 Borosilicate glass starts to deform around 820 to 830°C and will become very soft at around 1250°C. A natural gas Bunsen burner set to a blue flame can reach temperatures of 900 to 1000°C, so you can see how glass could become deformed or misshapen at this temperature.