Fix add_constraints!

Author: ericphanson

src/problems.jl

@@ -95,10 +95,9 @@ satisfy(constraints::Array{<:Constraint}=Constraint[]; numeric_type = Float64) =
 satisfy(constraint::Constraint; numeric_type = Float64) = satisfy([constraint]; numeric_type = numeric_type)
 
 # +(constraints, constraints) is defined in constraints.jl
-add_constraints!(p::Problem, constraints::Array{<:Constraint}) =
-    +(p.constraints, constraints)
+add_constraints!(p::Problem, constraints::Array{<:Constraint}) = append!(p.constraints, constraints)
 add_constraints!(p::Problem, constraint::Constraint) = add_constraints!(p, [constraint])
-add_constraint! = add_constraints!
+const add_constraint! = add_constraints!
 
 # caches conic form of x when x is the solution to the optimization problem p
 function cache_conic_form!(conic_forms::UniqueConicForms, x::AbstractExpr, p::Problem)

test/test_utilities.jl

@@ -274,6 +274,23 @@ using Convex: AbstractExpr, ConicObj
         @test_logs  Convex.NotDcp()
         Convex.DCP_WARNINGS[] = true
         @test_logs (:warn, r"not DCP compliant") Convex.NotDcp()
-        
+
+    end
+
+    @testset "`add_constraints!` (#380)" begin
+        x = Variable(3, 3)
+        p = minimize(norm_1(x))
+        y = randn(3, 3)
+        c = (norm2(x-y) < 1)
+        @test length(p.constraints) == 0
+        add_constraint!(p, c)
+        @test length(p.constraints) == 1
+        empty!(p.constraints)
+        add_constraints!(p, c)
+        @test length(p.constraints) == 1
+        empty!(p.constraints)
+        c2 = (norm2(x-rand(3,3)) < 3)
+        add_constraints!(p, [c, c2])
+        @test length(p.constraints) == 2
     end
 end