From 56e23e33363498b2f9be02db41d425beec8f4499 Mon Sep 17 00:00:00 2001
From: Rich FitzJohn <r.fitzjohn@imperial.ac.uk>
Date: Fri, 3 May 2024 09:20:11 +0100
Subject: [PATCH] Basic testing

---
 inst/include/dust2/cpu.hpp       |  2 +-
 inst/include/dust2/r/helpers.hpp |  2 +-
 tests/testthat/test-walk.R       | 98 ++++++++++++++++++++++++++++++++
 3 files changed, 100 insertions(+), 2 deletions(-)

diff --git a/inst/include/dust2/cpu.hpp b/inst/include/dust2/cpu.hpp
index 1f50d3f2..de222253 100644
--- a/inst/include/dust2/cpu.hpp
+++ b/inst/include/dust2/cpu.hpp
@@ -31,7 +31,7 @@ class dust_cpu {
     rng_(n_particles_, seed, deterministic) {
     // TODO: above, filter states need adding here too.
     if (dt != 1) {
-      throw std::runtime_error("Assuming dt = 1 for now");
+      throw std::runtime_error("Requiring dt = 1 for now");
     }
   }
 
diff --git a/inst/include/dust2/r/helpers.hpp b/inst/include/dust2/r/helpers.hpp
index 1ee418d2..d2228b94 100644
--- a/inst/include/dust2/r/helpers.hpp
+++ b/inst/include/dust2/r/helpers.hpp
@@ -5,7 +5,7 @@ namespace r {
 
 inline void check_scalar(cpp11::sexp x, const char * name) {
   if (LENGTH(x) != 1) {
-    cpp11::stop("'%s' must be scalar", name);
+    cpp11::stop("'%s' must be a scalar", name);
   }
 }
 
diff --git a/tests/testthat/test-walk.R b/tests/testthat/test-walk.R
index 51042fc8..b0a928b5 100644
--- a/tests/testthat/test-walk.R
+++ b/tests/testthat/test-walk.R
@@ -18,3 +18,101 @@ test_that("can run simple walk model", {
   expect_equal(s, colSums(r$normal(3, 0, 1)))
   expect_equal(dust2_cpu_walk_time(ptr), 3)
 })
+
+
+test_that("can set model state from a vector", {
+  pars <- list(sd = 1, random_initial = TRUE)
+  obj <- dust2_cpu_walk_alloc(pars, 0, 1, 10, 42, FALSE)
+  ptr <- obj[[1]]
+  s <- runif(10)
+  expect_null(dust2_cpu_walk_set_state(ptr, s))
+  expect_equal(dust2_cpu_walk_state(ptr), s)
+
+  expect_null(dust2_cpu_walk_run_steps(ptr, 3))
+
+  r <- mcstate2::mcstate_rng$new(seed = 42, n_streams = 10)
+  expect_equal(dust2_cpu_walk_state(ptr),
+               colSums(r$normal(3, 0, 1)) + s)
+})
+
+
+test_that("can set model state from initial conditions", {
+  pars <- list(sd = 1, random_initial = TRUE)
+  obj <- dust2_cpu_walk_alloc(pars, 0, 1, 10, 42, FALSE)
+  ptr <- obj[[1]]
+  expect_null(dust2_cpu_walk_set_state_initial(ptr))
+  r <- mcstate2::mcstate_rng$new(seed = 42, n_streams = 10)
+  expect_equal(dust2_cpu_walk_state(ptr),
+               drop(r$normal(1, 0, 1)))
+})
+
+
+## Not 100% sure we'll keep this, but we will see.  This is only a
+## feature of the walk model and not dust though.
+test_that("can set model state from initial conditions with empty version", {
+  pars <- list(sd = 1)
+  obj <- dust2_cpu_walk_alloc(pars, 0, 1, 10, 42, FALSE)
+  ptr <- obj[[1]]
+  expect_null(dust2_cpu_walk_set_state_initial(ptr))
+  expect_equal(dust2_cpu_walk_state(ptr),
+               rep(0, 10))
+})
+
+
+test_that("can run deterministically", {
+  pars <- list(sd = 1)
+  obj <- dust2_cpu_walk_alloc(pars, 0, 1, 10, 42, TRUE)
+  ptr <- obj[[1]]
+  expect_null(dust2_cpu_walk_run_steps(ptr, 3))
+  expect_equal(dust2_cpu_walk_state(ptr),
+               rep(0, 10))
+})
+
+
+test_that("require that dt is 1 for now", {
+  pars <- list(sd = 1, random_initial = TRUE)
+  expect_error(
+    dust2_cpu_walk_alloc(pars, 0, 0.5, 10, 42, FALSE),
+    "Requiring dt = 1 for now",
+    fixed = TRUE)
+})
+
+
+## Not a test at all of the model, but of the error handling in
+## r/helpers.hpp
+test_that("validate inputs", {
+  pars <- list(sd = 1, random_initial = TRUE)
+  expect_error(
+    dust2_cpu_walk_alloc(pars, 0:3, 1, 10, 42, FALSE),
+    "'time' must be a scalar")
+
+  expect_identical(
+    dust2_cpu_walk_time(dust2_cpu_walk_alloc(pars, 5L, 1, 10, 42, FALSE)[[1]]),
+    5.0)
+  expect_identical(
+    dust2_cpu_walk_time(dust2_cpu_walk_alloc(pars, 5, 1, 10, 42, FALSE)[[1]]),
+    5.0)
+  expect_error(
+    dust2_cpu_walk_alloc(pars, "5", 1, 10, 42, FALSE),
+    "'time' must be scalar numeric")
+
+  expect_identical(
+    dust2_cpu_walk_state(dust2_cpu_walk_alloc(pars, 5, 1, 10, 42, FALSE)[[1]]),
+    rep(0, 10))
+  expect_identical(
+    dust2_cpu_walk_state(dust2_cpu_walk_alloc(pars, 5, 1, 10L, 42, FALSE)[[1]]),
+    rep(0, 10))
+  expect_error(
+    dust2_cpu_walk_alloc(pars, 5, 1, 9.5, 42, FALSE),
+    "'n_particles' must be integer-like")
+  expect_error(
+    dust2_cpu_walk_alloc(pars, 5, 1, "10", 42, FALSE),
+    "'n_particles' must be scalar integer")
+  expect_error(
+    dust2_cpu_walk_alloc(pars, 5, 1, -5, 42, FALSE),
+    "'n_particles' must be non-negative")
+
+  expect_error(
+    dust2_cpu_walk_alloc(pars, 5, 1, 10, 42, 1),
+    "'deterministic' must be scalar logical")
+})