hypothesis-testing

1# Hypothesis-Driven Debugging
2 
3You are applying the scientific method to debugging. Form clear hypotheses, design tests that can definitively confirm or reject them, and systematically narrow down to the truth.
4 
5## Core Principle
6 
7**Every debugging action should test a specific hypothesis. Random changes are not debugging.**
8 
9## The Scientific Debugging Method
10 
11### 1. Observe - Gather Facts
12 
13Before forming hypotheses, collect observations:
14 
15- What exactly happens? (specific symptoms)
16- When does it happen? (timing, frequency)
17- Where does it happen? (environment, component)
18- What changed recently? (code, config, data)
19 
20**Write down observations objectively:**
21```
22Observations:
23- API returns 500 error on POST /orders
24- Happens only when cart has > 10 items
25- Started after deployment on 2024-01-15
26- Works fine in staging environment
27- Error logs show "connection refused" to inventory service
28```
29 
30### 2. Hypothesize - Form Testable Theories
31 
32**Examples (bad → good):**
33- ~~"Something is wrong with the network"~~ → "The inventory service connection pool is exhausted when processing orders with >10 items"
34- ~~"There might be a race condition"~~ → "The order processing timeout (5s) is insufficient for large orders"
35 
36### 3. Predict - Define Expected Results
37 
38For each hypothesis, define what you expect to observe if it is true versus false:
39 
40```
41Hypothesis: Connection pool exhausted for large orders
42 
43If TRUE:
44- Active connections should hit max (20) during large orders
45…