Table of Contents

Settings reference

ConjectureSettings controls engine behavior per-test or across an assembly.

Settings precedence

Settings are resolved in this order (most specific wins):

  1. [Property] attribute — per-test overrides
  2. [assembly: ConjectureSettings] — assembly-level defaults
  3. Built-in defaults — ConjectureSettings record defaults

Complete settings table

Property Type Default Description
MaxExamples int 100 Number of generated examples per test. Must be > 0.
Seed ulong? null Fixed PRNG seed for reproducibility. null = random. On [Property], use ulong where 0 = random.
UseDatabase bool true Persist and replay failing examples across runs.
DatabasePath string ".conjecture/examples/" Directory for the example database.
Deadline TimeSpan? null Per-example timeout. null = no deadline. On [Property], use DeadlineMs (int milliseconds; 0 = no deadline).
MaxStrategyRejections int 5 Max consecutive rejections by a single Where() filter before throwing. Must be ≥ 0.
MaxUnsatisfiedRatio int 200 Max ratio of skipped-to-valid examples before the test is marked as too flaky. Must be ≥ 0.
Targeting bool true Enable or disable the targeted testing phase (hill climbing after generation).
TargetingProportion double 0.5 Fraction of MaxExamples reserved for targeting. Must be in [0.0, 1.0).
Logger ILogger NullLogger.Instance Structured logging sink. Adapters auto-wire framework output.
ExportReproOnFailure bool false Write the shrunk counterexample byte buffer to a file on failure.
ReproOutputPath string ".conjecture/repros/" Directory for exported repro files. Used when ExportReproOnFailure = true.

[Property] attribute properties

These properties are available on the [Property] attribute (per-test only):

Property Type Default Notes
MaxExamples int 100
Seed ulong 0 0 = random seed
UseDatabase bool true
MaxStrategyRejections int 5
DeadlineMs int 0 0 = no deadline
Targeting bool true
TargetingProportion double 0.5
ExportReproOnFailure bool false
ReproOutputPath string ".conjecture/repros/"

Assembly-level defaults

Apply settings to all tests in an assembly:

// In any .cs file in your test project:
using Conjecture.Core;

[assembly: ConjectureSettings(MaxExamples = 500, UseDatabase = false)]

Programmatic settings

The ConjectureSettings record is immutable and supports with expressions:

ConjectureSettings defaults = new();
ConjectureSettings ci = defaults with { MaxExamples = 1000, UseDatabase = false };
ConjectureSettings debug = defaults with { Seed = 42UL, Deadline = TimeSpan.FromSeconds(30) };

Common configurations

CI — more examples, no database

[assembly: ConjectureSettings(MaxExamples = 1000, UseDatabase = false)]

Debugging — reproduce a specific failure

[Property(Seed = 0xDEADBEEF12345678)]
public bool Debugging_this_test(int value) => ...;

Per-example deadline — catch performance regressions

[Property(DeadlineMs = 1000)]
public bool Sort_is_fast(List<int> items)
{
    MySort.Sort(items);
    return true;
}

Relaxed filtering — heavy Assume.That usage

[assembly: ConjectureSettings(MaxStrategyRejections = 20, MaxUnsatisfiedRatio = 500)]

See also

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