From dd67abbc3dbc4d083ce3887931c3da6079fb419d Mon Sep 17 00:00:00 2001
From: Aayush Sabharwal <aayush.sabharwal@juliahub.com>
Date: Mon, 17 Jun 2024 11:06:56 +0530
Subject: [PATCH] fix: fix and test `getu` and `getp` with empty arrays

---
 src/parameter_indexing.jl       |  3 +++
 src/state_indexing.jl           |  2 +-
 test/parameter_indexing_test.jl | 15 +++++++++++++++
 test/state_indexing_test.jl     | 18 ++++++++++++++++++
 4 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/src/parameter_indexing.jl b/src/parameter_indexing.jl
index de2d6caf..ed793762 100644
--- a/src/parameter_indexing.jl
+++ b/src/parameter_indexing.jl
@@ -323,6 +323,9 @@ struct MultipleParametersGetter{T <: IsIndexerTimeseries, G, I} <:
 end
 
 function MultipleParametersGetter(getters)
+    if isempty(getters)
+        return MultipleParametersGetter{IndexerNotTimeseries, typeof(getters), Nothing}(getters, nothing)
+    end
     has_timeseries_indexers = any(getters) do g
         is_indexer_timeseries(g) == IndexerTimeseries()
     end
diff --git a/src/state_indexing.jl b/src/state_indexing.jl
index 25d18666..b17e417e 100644
--- a/src/state_indexing.jl
+++ b/src/state_indexing.jl
@@ -236,7 +236,7 @@ for (t1, t2) in [
     @eval function _getu(sys, ::NotSymbolic, ::$t1, sym::$t2)
         num_observed = count(x -> is_observed(sys, x), sym)
         if num_observed == 0 || num_observed == 1 && sym isa Tuple
-            if all(Base.Fix1(is_parameter, sys), sym) &&
+            if !isempty(sym) && all(Base.Fix1(is_parameter, sys), sym) &&
                all(!Base.Fix1(is_timeseries_parameter, sys), sym)
                 GetpAtStateTime(getp(sys, sym))
             else
diff --git a/test/parameter_indexing_test.jl b/test/parameter_indexing_test.jl
index 5b392ab1..c32b4e37 100644
--- a/test/parameter_indexing_test.jl
+++ b/test/parameter_indexing_test.jl
@@ -123,9 +123,19 @@ for sys in [
                 @test buffer == collect(val)
             end
         end
+
+        getter = getp(sys, [])
+        @test getter(fi) == []
     end
 end
 
+let
+    sc = SymbolCache(nothing, nothing, :t)
+    fi = FakeIntegrator(sc, nothing, 0.0, Ref(0))
+    getter = getp(sc, [])
+    @test getter(fi) == []
+end
+
 struct MyDiffEqArray
     t::Vector{Float64}
     u::Vector{Vector{Float64}}
@@ -387,6 +397,11 @@ end
 
 @test_throws ErrorException getp(sys, :not_a_param)
 
+let fs = fs, sys = sys
+    getter = getp(sys, [])
+    @test getter(fs) == []
+end
+
 struct FakeNoTimeSolution
     sys::SymbolCache
     u::Vector{Float64}
diff --git a/test/state_indexing_test.jl b/test/state_indexing_test.jl
index d8392636..d4a3f6ac 100644
--- a/test/state_indexing_test.jl
+++ b/test/state_indexing_test.jl
@@ -91,6 +91,15 @@ for (sym, val, check_inference) in [
     @test get(fi) == val
 end
 
+let fi = fi, sys = sys
+    getter = getu(sys, [])
+    @test getter(fi) == []
+    sc = SymbolCache(nothing, [:a, :b], :t)
+    fi = FakeIntegrator(sys, nothing, [1.0, 2.0], 3.0)
+    getter = getu(sc, [])
+    @test getter(fi) == []
+end
+
 for (sym, oldval, newval, check_inference) in [(:a, p[1], 4.0, true)
                                                (:b, p[2], 5.0, true)
                                                (:c, p[3], 6.0, true)
@@ -232,6 +241,15 @@ for (sym, val) in [(:a, p[1])
     @test get(sol) == val
 end
 
+let sol = sol, sys = sys
+    getter = getu(sys, [])
+    @test getter(sol) == [[] for _ in 1:length(sol.t)]
+    sc = SymbolCache(nothing, [:a, :b], :t)
+    sol = FakeSolution(sys, nothing, [1.0, 2.0], [0.0])
+    getter = getu(sc, [])
+    @test getter(sol) == [[]]
+end
+
 sys = SymbolCache([:x, :y, :z], [:a, :b, :c])
 u = [1.0, 2.0, 3.0]
 p = [10.0, 20.0, 30.0]