Implement model printing (#80)

* Implement model printing

* Simplify testing

Author: odow

src/LinQuadOptInterface.jl

@@ -199,6 +199,12 @@ end
 # Abstract + macro
 abstract type LinQuadOptimizer <: MOI.AbstractOptimizer end
 
+function Base.show(io::IO, model::LinQuadOptimizer)
+    println(io, "A LinQuadOptInterface model with backend:")
+    Base.show(io, model.inner)
+    return
+end
+
 @enum(VariableType, Continuous, Binary, Integer, Semiinteger, Semicontinuous)
 
 macro LinQuadOptimizerBase(inner_model_type=Any)

src/mockoptimizer.jl

@@ -80,6 +80,14 @@ mutable struct MockLinQuadModel # <: LinQuadOptInterface.LinQuadOptimizer
     end
 end
 
+function Base.show(io::IO, model::MockLinQuadModel)
+    println(io, "MockLinQuadModel")
+    println(io, "    Sense       $(model.sense)")
+    println(io, "    Variables   $(length(model.lb))")
+    println(io, "    Constraints $(length(model.b))")
+    return
+end
+
 """
 Solution builder to create solutions for the mock solver.
 Should be called inside `MOI.optimize!(model::LinQuadOptimizer)` right before changing signs. This means that these solutions replicate the low-level solver output.

test/runtests.jl

@@ -20,6 +20,12 @@ end
 @testset "LinQuadOptInterface" begin
     solver = LQOI.MockLinQuadOptimizer()
 
+    @testset "Printing" begin
+        @test sprint(show, solver) == "A LinQuadOptInterface model with " *
+            "backend:\nMockLinQuadModel\n    Sense       minimize\n    " *
+            "Variables   0\n    Constraints 0\n"
+    end
+
     config = MOIT.TestConfig(solve=false)
 
     @testset "Unit Tests" begin