add tests and extension boilerplate

.gitignore

@@ -4,3 +4,6 @@ Manifest.toml
 # vscode stuff
 .vscode
 .vscode/*
+
+# python extensions
+.CondaPkg

Project.toml

@@ -34,10 +34,12 @@ ZygoteRules = "700de1a5-db45-46bc-99cf-38207098b444"
 
 [weakdeps]
 PyCall = "438e738f-606a-5dbb-bf0a-cddfbfd45ab0"
+PythonCall = "6099a3de-0909-46bc-b1f4-468b9a2dfc0d"
 Zygote = "e88e6eb3-aa80-5325-afca-941959d7151f"
 
 [extensions]
 PyCallExt = "PyCall"
+PythonCallExt = "PythonCall"
 ZygoteExt = "Zygote"
 
 [compat]
@@ -72,11 +74,12 @@ DelayDiffEq = "bcd4f6db-9728-5f36-b5f7-82caef46ccdb"
 OrdinaryDiffEq = "1dea7af3-3e70-54e6-95c3-0bf5283fa5ed"
 Pkg = "44cfe95a-1eb2-52ea-b672-e2afdf69b78f"
 PyCall = "438e738f-606a-5dbb-bf0a-cddfbfd45ab0"
+PythonCall = "6099a3de-0909-46bc-b1f4-468b9a2dfc0d"
 SafeTestsets = "1bc83da4-3b8d-516f-aca4-4fe02f6d838f"
 StaticArrays = "90137ffa-7385-5640-81b9-e52037218182"
 StochasticDiffEq = "789caeaf-c7a9-5a7d-9973-96adeb23e2a0"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 Zygote = "e88e6eb3-aa80-5325-afca-941959d7151f"
 
 [targets]
-test = ["Pkg", "PyCall", "SafeTestsets", "Test", "StaticArrays", "StochasticDiffEq", "Aqua", "Zygote"]
+test = ["Pkg", "PyCall", "PythonCall", "SafeTestsets", "Test", "StaticArrays", "StochasticDiffEq", "Aqua", "Zygote"]

test/python/Project.toml

@@ -1,9 +1,13 @@
 [deps]
+DifferentialEquations = "0c46a032-eb83-5123-abaf-570d42b7fbaa"
 OrdinaryDiffEq = "1dea7af3-3e70-54e6-95c3-0bf5283fa5ed"
 PyCall = "438e738f-606a-5dbb-bf0a-cddfbfd45ab0"
+PythonCall = "6099a3de-0909-46bc-b1f4-468b9a2dfc0d"
 SciMLBase = "0bca4576-84f4-4d90-8ffe-ffa030f20462"
 
 [compat]
+DifferentialEquations = "7.11"
 OrdinaryDiffEq = "6.33"
 PyCall = "1.96"
+PythonCall = "0.9.14"
 SciMLBase = "2"

test/python/pythoncall.jl

@@ -0,0 +1,69 @@
+using DifferentialEquations, PythonCall
+
+@testset "Use of DifferentialEquations through PythonCall with user code written in Python" begin
+    pyexec("""
+    from juliacall import Main
+    de = Main.seval("DifferentialEquations")
+
+    def f(u,p,t):
+        return -u
+
+    u0 = 0.5
+    tspan = (0., 1.)
+    prob = de.ODEProblem(f, u0, tspan)
+    sol = de.solve(prob)
+    """, @__MODULE__)
+    @test pyconvert(Any, pyeval("sol", @__MODULE__)) isa ODESolution
+
+    pyexec("""
+    def f(u,p,t):
+        x, y, z = u
+        sigma, rho, beta = p
+        return [sigma * (y - x), x * (rho - z) - y, x * y - beta * z]
+
+    u0 = [1.0,0.0,0.0]
+    tspan = (0., 100.)
+    p = [10.0,28.0,8/3]
+    prob = de.ODEProblem(f, u0, tspan, p)
+    sol = de.solve(prob,saveat=0.01)
+    """, @__MODULE__)
+    @test pyconvert(Any, pyeval("sol", @__MODULE__)) isa ODESolution
+
+    # TODO: test the types and shapes of sol.t and de.transpose(de.stack(sol.u)) but don't actually plot them in CI
+    # pyexec("""
+    # import matplotlib.pyplot as plt
+
+    # plt.plot(sol.t, de.transpose(de.stack(sol.u))) # :( fails without the conversion
+    # plt.show()
+    # """, @__MODULE__)
+
+    @pyexec """
+    jul_f = Main.seval(""\"
+    function f(du,u,p,t)
+        x, y, z = u
+        sigma, rho, beta = p
+        du[1] = sigma * (y - x)
+        du[2] = x * (rho - z) - y
+        du[3] = x * y - beta * z
+    end""\")
+    u0 = [1.0,0.0,0.0]
+    tspan = (0., 100.)
+    p = [10.0,28.0,2.66]
+    prob = de.ODEProblem(jul_f, u0, tspan, p)
+    sol = de.solve(prob)
+    """
+    @test pyconvert(Any, pyeval("sol", @__MODULE__)) isa ODESolution
+
+    pyexec("""
+    def f(u,p,t):
+        return 1.01*u
+
+    def g(u,p,t):
+        return 0.87*u
+
+    u0 = 0.5
+    tspan = (0.0,1.0)
+    prob = de.SDEProblem(f,g,u0,tspan)
+    sol = de.solve(prob,reltol=1e-3,abstol=1e-3)
+    """, @__MODULE__)
+end

test/runtests.jl

@@ -105,5 +105,8 @@ end
         @time @safetestset "PyCall" begin
             include("python/pycall.jl")
         end
+        @time @safetestset "PythonCall" begin
+            include("python/pythoncall.jl")
+        end
     end
 end