Br- and I- ions give layer test, but Cl- ion doesn't. Why?
Organic Layer test is a test involving redox reactions among halides. This test is used to detect in the presence of bromide ions and iodide ions in a solution (e.g., Lassaigne’s test solution).  Layer test is carried out by adding organic solvent such as carbon disulphide or chloroform in the presence of nitric acid and chlorine water to the given solution. For example, Lassaigne’s extract is acidified with dilute nitric acid and chlorine water is added to it. When organic solvent is added to this aqueous solution and shaken the mixture vigorously but carefully, the liberated bromine or iodine liberated by redox reaction of bromide or iodide ions with chlorine) would be traveled to organic layer to give distinguished color. In case bromine is present, it will give an orange layer while it will give a violet layer in case of presence of Iodine. Relevant redox reactions are given below:

$$\ce{Br- + Cl2 -&gt; Br2 + Cl-}$$
$$\ce{I- + Cl2 -&gt; I2 + Cl-}$$

The key is bromine and iodine are much soluble in organic solvents than in water. Since we are using chlorine as a oxidant, chloride ions are negated here.