Added more unit tests

tools/python/test/test_global_optimization.py

 from dlib import find_max_global, find_min_global
+import dlib
 from pytest import raises
+from math import sin,cos,pi,exp,sqrt,pow
 
 
 def test_global_optimization_nargs():
@@ -23,9 +25,39 @@ def test_global_optimization_nargs():
         find_min_global(lambda a, b, c, d, *args: 0, [0, 0, 0], [1, 1, 1], 10)
 
 
+def F(a,b):
+    return -pow(a-2,2.0) - pow(b-4,2.0);
+def G(x):
+    return 2-pow(x-5,2.0); 
+
+def test_global_function_search():
+    spec_F = dlib.function_spec([-10,-10], [10,10])
+    spec_G = dlib.function_spec([-2], [6])
+
+    opt = dlib.global_function_search([spec_F, spec_G])
+
+    for i in range(15):
+        next = opt.get_next_x()
+        #print("next x is for function {} and has coordinates {}".format(next.function_idx, next.x))
+        
+        if (next.function_idx == 0):
+            a = next.x[0]
+            b = next.x[1]
+            next.set(F(a,b))
+        else:
+            x = next.x[0]
+            next.set(G(x))
+
+    [x,y,function_idx] = opt.get_best_function_eval()
+
+    #print("\nbest function was {}, with y of {}, and x of {}".format(function_idx,y,x))
+
+    assert(abs(y-2) < 1e-7)
+    assert(abs(x[0]-5) < 1e-7)
+    assert(function_idx==1)
+
 
 
-from math import sin,cos,pi,exp,sqrt
 def holder_table(x0,x1):
     return -abs(sin(x0)*cos(x1)*exp(abs(1-sqrt(x0*x0+x1*x1)/pi)))