lambertw: test maxiter= and convergence warning

Author: alyst

src/lambertw.jl

@@ -137,7 +137,7 @@ function lambertw_root_finding(z::T, x0::T, maxits::Integer) where T <: Number
         lastx = x
         lastdiff = xdiff
     end
-    converged || @warn("lambertw(", z, ") did not converge in ", maxits, " iterations.")
+    converged || @warn "lambertw($z) did not converge in $maxits iterations."
     return x
 end
 

test/lambertw.jl

@@ -77,6 +77,12 @@ end
 @test lambertw(complex(-3.0, -4.0), 1) ≈ Complex(0.5887666813694675, 2.7118802109452247) atol=1e-14
 @test lambertw(complex(.3, .3)) ≈ Complex(0.26763519642648767, 0.1837481231767825)
 
+# test maxiter keyword and convergence warning
+@test_logs (:warn, "lambertw(-0.2) did not converge in 3 iterations.") @inferred(lambertw(-0.2, -1, maxiter=3))
+@test lambertw(-0.2, -1, maxiter=5) == lambertw(-0.2, -1)
+@test_logs (:warn, "lambertw(0.3 + 0.3im) did not converge in 3 iterations.") @inferred(lambertw(complex(.3, .3), maxiter=3))
+@test lambertw(complex(.3, .3), maxiter=5) == lambertw(complex(.3, .3))
+
 # bug fix
 # The routine will start at -1/e + eps * im, rather than -1/e + 0im,
 # otherwise root finding will fail