public void Value_AfterMutation_ReturnsTheExpectedValue()
{
var mutable = D.Mutable("ok");
var pure = new PureDependency <string>(mutable, () => $"<<{mutable.Value.ToUpperInvariant()}>>");
Assert.Equal("<<OK>>", pure.Value);
mutable.Value = "changed";
Assert.Equal("<<CHANGED>>", pure.Value);
}
public void Mark_WhenTheValueHasntBeenObserved_UnsubscribesFromDependencies()
{
var stubDependency = new StubDependency();
var markedDirty = 0;
var sweptDirty = 0;
var pure = new PureDependency <string>(stubDependency, () => "OK");
pure.MarkInvalidated += (sender, args) => markedDirty++;
pure.SweepInvalidated += (sender, args) => sweptDirty++;
// Before observing the value, there should be no subscription.
Assert.Empty(stubDependency.Marks);
Assert.Empty(stubDependency.Sweeps);
var fresh = pure.TryPeek(out var peek);
Assert.False(fresh);
// Observing the value should return the expected string.
Assert.Equal("OK", pure.Value);
Assert.Equal(0, markedDirty);
Assert.Equal(0, sweptDirty);
// After observing the value, the subscription should be estiablished, and the value should be peek-able.
Assert.Single(stubDependency.Marks);
Assert.Single(stubDependency.Sweeps);
fresh = pure.TryPeek(out peek);
Assert.True(fresh);
Assert.Equal("OK", peek);
// Mark the value dirty and sweep.
stubDependency.Marks.Single().Invoke(this, EventArgs.Empty);
stubDependency.Sweeps.Single().Invoke(this, EventArgs.Empty);
Assert.Equal(1, markedDirty);
Assert.Equal(1, sweptDirty);
// After the first dirty, the subscription should be maintianed, but it should not be fresh.
Assert.Single(stubDependency.Marks);
Assert.Single(stubDependency.Sweeps);
fresh = pure.TryPeek(out peek);
Assert.False(fresh);
Assert.Equal("OK", peek);
// Mark the value dirty and sweep again.
stubDependency.Marks.Single().Invoke(this, EventArgs.Empty);
stubDependency.Sweeps.SingleOrDefault()?.Invoke(this, EventArgs.Empty);
Assert.Equal(1, markedDirty);
Assert.Equal(1, sweptDirty);
// After the second dirty, the subscription should be disposed and the references should be destroyed.
Assert.Empty(stubDependency.Marks);
Assert.Empty(stubDependency.Sweeps);
fresh = pure.TryPeek(out peek);
Assert.False(fresh);
Assert.Null(peek);
}
public void Value_WhenInvokedRepeatedly_OnlyInvokesTheEvaluationFunctionOnce()
{
var invocations = 0;
var evaluate = new Func <string>(() =>
{
Interlocked.Increment(ref invocations);
return("OK");
});
var depenedency = new PureDependency <string>(new StubDependency(), evaluate);
var values = new HashSet <string>
{
depenedency.Value,
depenedency.Value,
depenedency.Value,
};
Assert.Equal(1, invocations);
Assert.Equal("OK", values.Single());
}