Skilled Bug Investigation Illustrated - Reproducing the problem

In a presentation titled Skilled Testers and Their Enemies, James Bach identifies the steps involved in skilled bug investigation:

The following post is part of a 13-part series illustrating those points using A Study in Scarlet by Arthur Conan Doyle.

How can the problem be reproduced?

The cause of death (which could be considered the bug by some) was poison. Here Holmes proves it:

“Give them here,” said Holmes. “Now, Doctor,” turning to me, “are those ordinary pills?”

They certainly were not. They were of a pearly gray colour, small, round, and almost transparent against the light. “From their lightness and transparency, I should imagine that they are soluble in water,” I remarked.

“Precisely so,” answered Holmes. ‘Now would you mind going down and fetching that poor little devil of a terrier which has been bad so long, and which the landlady wanted you to put out of its pain yesterday?”

I went downstairs and carried the dog upstairs in my arms. Its laboured breathing and glazing eye showed that it was not far from its end. Indeed, its snow-white muzzle proclaimed that it had already exceeded the usual term of canine existence. I placed it upon a cushion on the rug.


With a perfect shriek of delight he rushed to the box, cut the other pill in two, dissolved it, added milk, and presented it to the terrier. The unfortunate creature’s tongue seemed hardly to have been moistened in it before it gave a convulsive shiver in every limb, and lay as rigid and lifeless as if it had been struck by lightning.