graph TB
    subgraph Era1["Era 1: Sequential"]
        A1[Single Core]
    end
    subgraph Era2["Era 2: Concurrent"]
        A2[Multi Core]
        B2[Single Machine]
    end
    subgraph Era3["Era 3: Distributed"]
        A3[Multi Core]
        B3[Multi Machine]
        C3[Single User]
    end
    subgraph Era4["Era 4: Multi-tenant"]
        A4[Multi Core]
        B4[Multi Machine]
        C4[Multi User]
        D4[Trusted]
    end
    subgraph Era5["Era 5: Adversarial"]
        A5[Multi Core]
        B5[Multi Machine]
        C5[Multi User]
        D5[Untrusted]
    end
    
    Era1 --> Era2 --> Era3 --> Era4 --> Era5

    style Era1 fill:#4ade80
    style Era2 fill:#facc15
    style Era3 fill:#f97316
    style Era4 fill:#ec4899
    style Era5 fill:#8b5cf6

flowchart TD
    subgraph S1["Sequential Testing"]
        T1["Unit Tests<br/>TDD<br/>Coverage"]
    end
    
    B1{{"Thread interleaving<br/>makes tests<br/>non-reproducible"}}
    
    subgraph S2["Concurrency Testing"]
        T2["Race Detectors<br/>Model Checking<br/>Systematic Scheduling"]
    end
    
    B2{{"Network partitions<br/>and partial failures<br/>across machines"}}
    
    subgraph S3["Distributed Testing"]
        T3["Chaos Engineering<br/>Jepsen<br/>Property-Based Testing"]
    end
    
    B3{{"Resource contention<br/>and tenant isolation<br/>requirements"}}
    
    subgraph S4["Multi-tenant Testing"]
        T4["Load Testing<br/>Contract Testing<br/>Canary Deployments"]
    end
    
    B4{{"Economic incentives<br/>to exploit<br/>vulnerabilities"}}
    
    subgraph S5["Adversarial Testing"]
        T5["Formal Verification<br/>Deterministic Simulation<br/>Bug Bounties"]
    end
    
    T1 --> B1 --> T2 --> B2 --> T3 --> B3 --> T4 --> B4 --> T5
    
    style B1 fill:#ff6b6b,color:#fff
    style B2 fill:#ff6b6b,color:#fff
    style B3 fill:#ff6b6b,color:#fff
    style B4 fill:#ff6b6b,color:#fff
    style S1 fill:#4ade80
    style S2 fill:#facc15
    style S3 fill:#f97316
    style S4 fill:#ec4899
    style S5 fill:#8b5cf6

graph TB
    subgraph Traditional["Traditional Testing Paradigm"]
        direction TB
        TT1["Sample behaviors"]
        TT2["Find bugs in tested scenarios"]
        TT3["Coverage = confidence"]
    end
    
    subgraph Adversarial["Adversarial Testing Paradigm"]
        direction TB
        AT1["Prove properties"]
        AT2["Guarantee invariants hold"]
        AT3["Proof = confidence"]
    end
    
    Traditional -->|"Economic attackers<br/>break the model"| Adversarial
    
    style Traditional fill:#f97316,color:#fff
    style Adversarial fill:#8b5cf6,color:#fff

timeline
    title Testing Tools Evolution
    
    section Sequential Era
        1989 : SUnit (Smalltalk)
        1997 : JUnit (Java)
        2003 : TDD by Example
        
    section Concurrency Era
        1997 : Eraser
        2007 : CHESS
        2009 : ThreadSanitizer v1
        2012 : ThreadSanitizer v2
        
    section Distributed Era
        2010 : Chaos Monkey
        2013 : Jepsen begins
        2000 : QuickCheck
        2010 : Dapper (tracing)
        
    section Multi-tenant Era
        2017 : SRE Book
        2013 : Pact
        2019 : OpenTelemetry
        
    section Adversarial Era
        2015 : AWS TLA+ paper
        2016 : DAO hack
        2020 : Echidna
        2025 : Certora open-source