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.

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What might be causing the problem?

Lestrade and Gregson glanced at each other with an incredulous smile.

“If this man was murdered, how was it done?” asked the former.

“Poison,” said Sherlock Holmes curtly, and strode off.

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.

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How severe could the problem be?

“Any delay in arresting the assassin,” I observed, “might give him time to perpetrate some fresh atrocity.”

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.

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What are the symptoms of the problem?

“There has been murder done, and the murderer was a man. He was more than six feet high, was in the prime of life, had small feet for his height, wore coarse, square-toed boots and smoked a Trichinopoly cigar. He came here with his victim in a four-wheeled cab, which was drawn by a horse with three old shoes and one new one on his off fore-leg. In all probability the murderer had a florid face, and the finger-nails of his right hand were remarkably long. These are only a few indications, but they may assist you.”

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.

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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.

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.

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Consider possibility of tester error

Holmes is certainly not the poster child for modesty. In fact, in this case he is completely confident of his abilities. It should be noted that in others he is not always so confident. In this tale, the closest I could come to admitting error is the following:

“‘Commonplace,’ said Holmes, though I thought from his expression that he was pleased at my evident surprise and admiration. ‘I said just now that there were no criminals. It appears that I am wrong — look at this!’ He threw me over the note which the commissionaire had brought.”