Add failing test

tests/testthat/test-poped.R

@@ -594,4 +594,33 @@ if (requireNamespace("PopED", quietly=TRUE)) {
   ## test_that("example 3", {
 
   ## })
+
+  test_that("PopED lhs", {
+
+    pheno <- function() {
+      ini({
+        tcl <- log(0.008) # typical value of clearance
+        tv <-  log(0.6)   # typical value of volume
+        ## var(eta.cl)
+        eta.cl + eta.v ~ c(1,
+                           0.01, 1) ## cov(eta.cl, eta.v), var(eta.v)
+        # interindividual variability on clearance and volume
+        add.err <- 0.1    # residual variability
+      })
+      model({
+        cl <- exp(tcl + eta.cl) # individual value of clearance
+        if (fed == 1)
+          cl <- cl*1.1
+        v <- exp(tv + eta.v)    # individual value of volume
+        ke <- cl / v            # elimination rate constant
+        d/dt(A1) = - ke * A1    # model differential equation
+        cp = A1 / v             # concentration in plasma
+        cp ~ add(add.err)       # define error model
+      })
+    }
+
+    p <- pheno()
+
+    expect_equal(eval(.popedRxModel(p))$lhs, c("rx_pred_", "rx_r_"))
+  })
 }