Roslyn analyzers reference

Conjecture includes Roslyn analyzers bundled in Conjecture.Core. They activate automatically — no additional packages needed.

Diagnostic rules

CON100: Assertion inside [Property] method

Severity: Warning
Target: void-returning [Property] methods that use framework assertions.

Consider returning bool for simpler, clearer tests.

// Triggers CON100:
[Property]
public void Bad(int value)
{
    Assert.True(value >= 0);  // CON100
}

// Preferred:
[Property]
public bool Good(int value) => value >= 0;

CON101: High-rejection Where() predicate

Severity: Warning
Target: .Where() predicates likely to reject most generated values.

High rejection rates cause poor performance and risk UnsatisfiedAssumptionException.

// Triggers CON101:
var primes = Generate.Integers<int>(0, 1_000_000).Where(IsPrime);

// Better: generate from a small known set
var primes = Generate.SampledFrom(new[] { 2, 3, 5, 7, 11, 13 });

CON102: Sync-over-async inside [Property]

Severity: Info
Target: .Result, .GetAwaiter().GetResult(), or .Wait() inside a [Property] method.

Make the method async instead.

// Triggers CON102:
[Property]
public bool Bad(int id)
{
    var result = _client.GetAsync($"/api/{id}").Result;  // CON102
    return result.IsSuccessStatusCode;
}

// Better:
[Property]
public async Task<bool> Good(int id)
{
    var result = await _client.GetAsync($"/api/{id}");
    return result.IsSuccessStatusCode;
}

CON103: Strategy bounds are inverted

Severity: Error
Target: Strategy factory calls where min > max.

// Triggers CON103:
Generate.Integers<int>(100, 0)  // min (100) > max (0)

// Fix:
Generate.Integers<int>(0, 100)

CON104: Assume.That(false) always skips

Severity: Warning
Target: Unconditional Assume.That(false) calls.

Every example is skipped — the test is effectively disabled.

// Triggers CON104:
Assume.That(false);  // test is useless

CON105: [Arbitrary] provider exists but [From<T>] not used

Severity: Info
Target: Parameters whose type has an [Arbitrary]-generated provider, but [From<T>] is absent.

[Arbitrary]
public partial record Money(decimal Amount, string Currency);

// Triggers CON105:
[Property]
public bool Test(Money money) => ...;

// Better:
[Property]
public bool Test([From<MoneyArbitrary>] Money money) => ...;

Source generator diagnostics

The [Arbitrary] source generator reports its own set of diagnostics:

ID	Severity	Description
CON200	Error	No accessible constructor found on [Arbitrary] type
CON201	Error	[Arbitrary] type is not partial
CON202	Warning	Constructor parameter type has no resolvable strategy

Suppressing diagnostics

Per-location:

#pragma warning disable CON100
[Property]
public void Intentionally_using_assertions(int value) { /* ... */ }
#pragma warning restore CON100

Project-wide via .editorconfig:

[*.cs]
dotnet_diagnostic.CON100.severity = none