Fix sorting for purely imag value

Author: jishnub

test/runtests.jl

@@ -2944,16 +2944,18 @@ end
 @testset "eigen" begin
     sortby = x -> (real(x), imag(x))
     @testset "AbstractFill" begin
-        @testset for val in (2.0, -2, 3+2im, 4 - 5im, 2im), n in (VERSION >= v"1.10" ? (0, 1, 4) : (1, 4))
+        sizes = VERSION >= v"1.10" ? (0, 1, 4) : (1, 4)
+        @testset for val in (2.0, -2, 3+2im, 4 - 5im, 2im), n in sizes
+            sortby_val = iszero(real(val)) ? imag : sortby
             F = Fill(val, n, n)
             M = Matrix(F)
-            @test eigvals(F; sortby) ≈ eigvals(M; sortby)
-            λ, V = eigen(F; sortby)
-            @test λ == eigvals(F; sortby)
+            @test eigvals(F; sortby = sortby_val) ≈ eigvals(M; sortby = sortby_val)
+            λ, V = eigen(F; sortby = sortby_val)
+            @test λ == eigvals(F; sortby = sortby_val)
             @test V'V ≈ I
             @test F * V ≈ V * Diagonal(λ)
         end
-        @testset for MT in (Ones, Zeros), T in (Float64, Int, ComplexF64), n in (0, 1, 4)
+        @testset for MT in (Ones, Zeros), T in (Float64, Int, ComplexF64), n in sizes
             F = MT{T}(n,n)
             M = Matrix(F)
             @test eigvals(F; sortby) ≈ eigvals(M; sortby)