Add start of parsing tests

tests/testthat/test-parse.R

@@ -0,0 +1,19 @@
+test_that("can parse trivial system", {
+  res <- odin_parse({
+    initial(x) <- 0
+    update(x) <- 0
+  })
+  expect_equal(res$time, "discrete")
+  expect_equal(res$class, "odin")
+  expect_mapequal(
+    res$location,
+    list(contents = list(variables = "x",
+                         shared = character(),
+                         internal = character(),
+                         data = character(),
+                         output = character(),
+                         stack = character()),
+         location = c(x = "state"),
+         type = c(x = "real_type"),
+         packing = list(state = list(x = 0))))
+})