Fix two problems with if-statements in equations

src/model.jl

@@ -1079,12 +1079,12 @@ function process_equation(model::Model, expr::Expr;
         filter!(!isnothing, args)
         if ex.head == :if
             if length(args) == 3
-                return Expr(:call, :if, args...)
+                return Expr(:if, args...)
             else
                 error_process("Unable to process an `if` statement with a single branch. Use function `ifelse` instead.", expr, modelmodule)
             end
         end
-        if ex.head ∈ (:call, :(&&), :(||))
+        if ex.head ∈ (:call, :comparison, :(&&), :(||))
             return Expr(ex.head, args...)
         end
         if ex.head == :block && length(args) == 1

test/runtests.jl

@@ -655,6 +655,30 @@ end
         end), eqn_name=:_EQ2) isa Equation
 end
 
+@testset "ifelse_eval" begin
+    # this addresses issue #70
+    @test let model = Model()
+        @variables model a
+        @parameters model cond = true
+        @equations model begin
+            :A => a[t] = cond ? 1.0 : -1.0
+        end
+        @initialize model
+        r, j = eval_RJ(zeros(1,1), model)
+        r == [-1.0] && j == [1.0;;]
+    end
+    @test let model = Model()
+        @variables model b
+        @parameters model p = 0.5
+        @equations model begin
+            :B => b[t] = (0.0 <= p <= 1.0) 
+        end
+        @initialize model
+        r, j = eval_RJ(zeros(1,1), model)
+        r == [-1.0] && j == [1.0;;]
+    end
+end
+
 @testset "Meta" begin
     mod = Model()
     @parameters mod a = 0.1 b = @link(1.0 - a)
@@ -1526,7 +1550,7 @@ end
 
 @using_example E2sat
 m2_for_sattelite_tests = E2sat.newmodel()
-@testset "sattelite models" begin
+@testset "satellite models" begin
     m1 = E2.newmodel()
 
     m_sattelite = Model()