Compact Diagnostic Test (CoDiT) procedure allows one to test mechanical properties of historic materials in a minor destructive way using micro-cores drilled out of a masonry wall. CoDiT procedure applied to brick masonry gives insight into the non-homogeneity of material properties both at a brick and a wall scale level. The test site was the orthodox monastery in Supraśl, north-east of Poland. Micro-cores of 6 mm in diameter were drilled out using diamond core drill bits. The micro-core samples were used to prepare specimens for optical, mechanical and ultrasonic testing of brick properties. Material parameters were measured, including tensile, bending and compressive strengths and longitudinal wave velocity together with optical analysis of sample inhomogeneities. It is shown that all these measurements can be done using specimens made of a single micro-core. The correlation between various measured parameters and applicability of CoDiT to measurement of old brick strength are also discussed.