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Restructured from flat .tex/.pdf files into per-paper subdirectories. Added Antje Worring as co-author on all papers. Synced PDFs to pdfs/ for download site.
48 lines
2.0 KiB
TeX
48 lines
2.0 KiB
TeX
\section{The Testing Pyramid for Distributed Systems}
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\subsection{Why a Pyramid}
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Different testing techniques catch different bug classes at different costs:
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\begin{table}[H]
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\centering
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\small
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\begin{tabular}{@{}llrrl@{}}
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\toprule
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\textbf{Layer} & \textbf{Technique} & \textbf{Cost} & \textbf{Speed} & \textbf{Catches} \\
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\midrule
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1 & Unit tests & Low & Fast & Logic bugs \\
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2 & Integration tests & Medium & Medium & Interface bugs \\
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3 & Property/fuzz tests & Medium & Medium & Edge cases, invariant violations \\
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4 & E2E tests & High & Slow & System-level regressions \\
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5 & Fault injection & High & Slow & Concurrency, network bugs \\
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6 & Model checking & High & Medium & Protocol design bugs \\
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7 & Formal proofs & Very high & Slow & Mathematical correctness \\
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\bottomrule
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\end{tabular}
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\caption{The testing pyramid. Lower layers are cheaper and run more frequently.}
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\end{table}
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The pyramid shape means: many unit tests (cheap, fast), fewer integration tests, even
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fewer E2E tests, and a handful of formal proofs (expensive, slow). Every layer is
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necessary---no layer substitutes for another.
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\subsection{What Each Layer Misses}
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\begin{itemize}[nosep]
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\item \textbf{Unit tests} miss: interactions between components, timing dependencies,
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network behavior.
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\item \textbf{Integration tests} miss: system-level emergent behavior, rare failure modes.
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\item \textbf{Property tests} miss: bugs that require specific state sequences (they test
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properties of individual operations, not sequences).
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\item \textbf{E2E tests} miss: rare timing conditions (they run the happy path and a few
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error paths).
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\item \textbf{Fault injection} misses: bugs in the protocol design (it tests the
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implementation, not the specification).
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\item \textbf{Model checking} misses: implementation bugs (it verifies the model, not the code).
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\item \textbf{Formal proofs} miss: everything that is not in the formal model.
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\end{itemize}
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%% ============================================================
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