What is the legal test for taking under colour of title?

Colour of title is co-extensive with the boundaries contained in the deed and does not extend to land beyond those boundaries. The doctrine, colour of title, is confined to cover those situations where a person enters upon lands under a document of title which purports on the face of it to cover all of the land the purchaser intended to purchase and for some reason unknown at the time to such person, the title is defective, in which case his possession of part of the land will be deemed constructive possession to all of it. Mr. Justice Burton in Harris v. Mudie, supra, explains the position of one who takes under colour of title as follows [at p. 428]: When a person so enters under a mere mistake as to his rights, purchasing or intending to purchase under what he believes to be a good title as from one whom he believes to be the heir-at-law or devisee under a will, or under a deed from a married woman defectively executed, or a forged deed, there is no good reason why his entry should not, as in the case of a valid deed, be coextensive with the supposed title, and come within the class of cases intended, in my opinion, to be protected by the statute; but it must in every case be a bona fide claim, and ought not lightly to be extended to a purchaser from a squatter or other person having no title, where the party has neglected to ascertain from the registry office, as he can always do in this country, whether the land has been patented, and who is the registered owner; and clearly not to cases where he knows the grantor has no title.