test: add tests for parse_variable

Author: AayushSabharwal

test/variable_utils.jl

@@ -1,6 +1,7 @@
 using ModelingToolkit, Test
-using ModelingToolkit: value, vars
+using ModelingToolkit: value, vars, parse_variable
 using SymbolicUtils: <ₑ
+
 @parameters α β δ
 expr = (((1 / β - 1) + δ) / α)^(1 / (α - 1))
 ref = sort([β, δ, α], lt = <ₑ)
@@ -41,3 +42,99 @@ ts = collect_ivs([eq])
     res = vars(fn([x, y], z))
     @test length(res) == 3
 end
+
+@testset "parse_variable" begin
+    @mtkmodel Lorenz begin
+        @variables begin
+            x(t)
+            y(t)
+            z(t)
+        end
+        @parameters begin
+            σ
+            ρ
+            β
+        end
+        @equations begin
+            D(D(x)) ~ σ * (y - x)
+            D(y) ~ x * (ρ - z) - y
+            D(z) ~ x * y - β * z
+        end
+    end
+    @mtkmodel ArrSys begin
+        @variables begin
+            x(t)[1:2]
+        end
+        @parameters begin
+            p[1:2, 1:2]
+        end
+        @equations begin
+            D(D(x)) ~ p * x
+        end
+    end
+    @mtkmodel Outer begin
+        @components begin
+            😄 = Lorenz()
+            arr = ArrSys()
+        end
+    end
+
+    @mtkbuild sys = Outer()
+    for (str, var) in [
+        # unicode system, scalar variable
+        ("😄.x", sys.😄.x),
+        ("😄.x(t)", sys.😄.x),
+        ("😄₊x", sys.😄.x),
+        ("😄₊x(t)", sys.😄.x),
+        # derivative
+        ("D(😄.x)", D(sys.😄.x)),
+        ("D(😄.x(t))", D(sys.😄.x)),
+        ("D(😄₊x)", D(sys.😄.x)),
+        ("D(😄₊x(t))", D(sys.😄.x)),
+        # other derivative
+        ("😄.xˍt", D(sys.😄.x)),
+        ("😄.x(t)ˍt", D(sys.😄.x)),
+        ("😄₊xˍt", D(sys.😄.x)),
+        ("😄₊x(t)ˍt", D(sys.😄.x)),
+        # scalar parameter
+        ("😄.σ", sys.😄.σ),
+        ("😄₊σ", sys.😄.σ),
+        # array variable
+        ("arr.x", sys.arr.x),
+        ("arr₊x", sys.arr.x),
+        ("arr.x(t)", sys.arr.x),
+        ("arr₊x(t)", sys.arr.x),
+        # getindex
+        ("arr.x[1]", sys.arr.x[1]),
+        ("arr₊x[1]", sys.arr.x[1]),
+        ("arr.x(t)[1]", sys.arr.x[1]),
+        ("arr₊x(t)[1]", sys.arr.x[1]),
+        # derivative
+        ("D(arr.x(t))", D(sys.arr.x)),
+        ("D(arr₊x(t))", D(sys.arr.x)),
+        ("D(arr.x[1])", D(sys.arr.x[1])),
+        ("D(arr₊x[1])", D(sys.arr.x[1])),
+        ("D(arr.x(t)[1])", D(sys.arr.x[1])),
+        ("D(arr₊x(t)[1])", D(sys.arr.x[1])),
+        # other derivative
+        ("arr.xˍt", D(sys.arr.x)),
+        ("arr₊xˍt", D(sys.arr.x)),
+        ("arr.xˍt(t)", D(sys.arr.x)),
+        ("arr₊xˍt(t)", D(sys.arr.x)),
+        ("arr.xˍt[1]", D(sys.arr.x[1])),
+        ("arr₊xˍt[1]", D(sys.arr.x[1])),
+        ("arr.xˍt(t)[1]", D(sys.arr.x[1])),
+        ("arr₊xˍt(t)[1]", D(sys.arr.x[1])),
+        ("arr.x(t)ˍt", D(sys.arr.x)),
+        ("arr₊x(t)ˍt", D(sys.arr.x)),
+        ("arr.x(t)ˍt[1]", D(sys.arr.x[1])),
+        ("arr₊x(t)ˍt[1]", D(sys.arr.x[1])),
+        # array parameter
+        ("arr.p", sys.arr.p),
+        ("arr₊p", sys.arr.p),
+        ("arr.p[1, 2]", sys.arr.p[1, 2]),
+        ("arr₊p[1, 2]", sys.arr.p[1, 2])
+    ]
+        isequal(parse_variable(sys, str), var)
+    end
+end