add adjust_bracket (#442)

Author: jverzani

Project.toml

@@ -1,6 +1,6 @@
 name = "Roots"
 uuid = "f2b01f46-fcfa-551c-844a-d8ac1e96c665"
-version = "2.1.7"
+version = "2.1.8"
 
 [deps]
 Accessors = "7d9f7c33-5ae7-4f3b-8dc6-eff91059b697"

src/Bracketing/chandrapatlu.jl

@@ -24,6 +24,7 @@ end
 # a = most recent, b prior
 function init_state(::Chandrapatla, F, x₀, x₁, fx₀, fx₁)
     a, b, fa, fb = x₁, x₀, fx₁, fx₀
+    assert_bracket(fa, fb)
     c, fc = a, fa
     ChandrapatlaState(promote(a, b, c)..., promote(fa, fb, fc)...)
 end

test/test_bracketing.jl

@@ -313,9 +313,9 @@ end
     @test avg(cnts) <= 3000
 
     ## issue 412 check for bracket
-    f = x -> x - 1
     for M in Ms
-        @test_throws ArgumentError find_zero(f, (-3, 0), M)
+        @test_throws ArgumentError find_zero(x -> x - 1, (-3, 0), M)
+        @test_throws ArgumentError find_zero(x -> 1 + x^2, (10, 20), M)
     end
 end