diff --git a/src/test_utils/models.jl b/src/test_utils/models.jl
index 4aa2aaa42..e721a75ef 100644
--- a/src/test_utils/models.jl
+++ b/src/test_utils/models.jl
@@ -323,28 +323,30 @@ function varnames(model::Model{typeof(demo_assume_dot_observe)})
     return [@varname(s), @varname(m)]
 end
 
-@model function demo_assume_observe_literal()
-    # `assume` and literal `observe`
+@model function demo_assume_multivariate_observe_literal()
+    # multivariate `assume` and literal `observe`
     s ~ product_distribution([InverseGamma(2, 3), InverseGamma(2, 3)])
     m ~ MvNormal(zeros(2), Diagonal(s))
     [1.5, 2.0] ~ MvNormal(m, Diagonal(s))
 
     return (; s=s, m=m, x=[1.5, 2.0], logp=getlogp(__varinfo__))
 end
-function logprior_true(model::Model{typeof(demo_assume_observe_literal)}, s, m)
+function logprior_true(model::Model{typeof(demo_assume_multivariate_observe_literal)}, s, m)
     s_dist = product_distribution([InverseGamma(2, 3), InverseGamma(2, 3)])
     m_dist = MvNormal(zeros(2), Diagonal(s))
     return logpdf(s_dist, s) + logpdf(m_dist, m)
 end
-function loglikelihood_true(model::Model{typeof(demo_assume_observe_literal)}, s, m)
+function loglikelihood_true(
+    model::Model{typeof(demo_assume_multivariate_observe_literal)}, s, m
+)
     return logpdf(MvNormal(m, Diagonal(s)), [1.5, 2.0])
 end
 function logprior_true_with_logabsdet_jacobian(
-    model::Model{typeof(demo_assume_observe_literal)}, s, m
+    model::Model{typeof(demo_assume_multivariate_observe_literal)}, s, m
 )
     return _demo_logprior_true_with_logabsdet_jacobian(model, s, m)
 end
-function varnames(model::Model{typeof(demo_assume_observe_literal)})
+function varnames(model::Model{typeof(demo_assume_multivariate_observe_literal)})
     return [@varname(s), @varname(m)]
 end
 
@@ -377,6 +379,30 @@ function varnames(model::Model{typeof(demo_dot_assume_observe_index_literal)})
     return [@varname(s[1]), @varname(s[2]), @varname(m[1]), @varname(m[2])]
 end
 
+@model function demo_assume_literal_observe()
+    # univariate `assume` and literal `observe`
+    s ~ InverseGamma(2, 3)
+    m ~ Normal(0, sqrt(s))
+    1.5 ~ Normal(m, sqrt(s))
+    2.0 ~ Normal(m, sqrt(s))
+
+    return (; s=s, m=m, x=[1.5, 2.0], logp=getlogp(__varinfo__))
+end
+function logprior_true(model::Model{typeof(demo_assume_literal_observe)}, s, m)
+    return logpdf(InverseGamma(2, 3), s) + logpdf(Normal(0, sqrt(s)), m)
+end
+function loglikelihood_true(model::Model{typeof(demo_assume_literal_observe)}, s, m)
+    return logpdf(Normal(m, sqrt(s)), 1.5) + logpdf(Normal(m, sqrt(s)), 2.0)
+end
+function logprior_true_with_logabsdet_jacobian(
+    model::Model{typeof(demo_assume_literal_observe)}, s, m
+)
+    return _demo_logprior_true_with_logabsdet_jacobian(model, s, m)
+end
+function varnames(model::Model{typeof(demo_assume_literal_observe)})
+    return [@varname(s), @varname(m)]
+end
+
 @model function demo_assume_literal_dot_observe()
     # `assume` and literal `dot_observe`
     s ~ InverseGamma(2, 3)
@@ -575,7 +601,8 @@ const DemoModels = Union{
     Model{typeof(demo_dot_assume_observe_index)},
     Model{typeof(demo_assume_dot_observe)},
     Model{typeof(demo_assume_literal_dot_observe)},
-    Model{typeof(demo_assume_observe_literal)},
+    Model{typeof(demo_assume_literal_observe)},
+    Model{typeof(demo_assume_multivariate_observe_literal)},
     Model{typeof(demo_dot_assume_observe_index_literal)},
     Model{typeof(demo_assume_submodel_observe_index_literal)},
     Model{typeof(demo_dot_assume_observe_submodel)},
@@ -585,7 +612,9 @@ const DemoModels = Union{
 }
 
 const UnivariateAssumeDemoModels = Union{
-    Model{typeof(demo_assume_dot_observe)},Model{typeof(demo_assume_literal_dot_observe)}
+    Model{typeof(demo_assume_dot_observe)},
+    Model{typeof(demo_assume_literal_dot_observe)}
+    Model{typeof(demo_assume_literal_observe)}
 }
 function posterior_mean(model::UnivariateAssumeDemoModels)
     return (s=49 / 24, m=7 / 6)
@@ -609,7 +638,7 @@ const MultivariateAssumeDemoModels = Union{
     Model{typeof(demo_assume_index_observe)},
     Model{typeof(demo_assume_multivariate_observe)},
     Model{typeof(demo_dot_assume_observe_index)},
-    Model{typeof(demo_assume_observe_literal)},
+    Model{typeof(demo_assume_multivariate_observe_literal)},
     Model{typeof(demo_dot_assume_observe_index_literal)},
     Model{typeof(demo_assume_submodel_observe_index_literal)},
     Model{typeof(demo_dot_assume_observe_submodel)},
@@ -759,9 +788,10 @@ const DEMO_MODELS = (
     demo_assume_multivariate_observe(),
     demo_dot_assume_observe_index(),
     demo_assume_dot_observe(),
-    demo_assume_observe_literal(),
+    demo_assume_multivariate_observe_literal(),
     demo_dot_assume_observe_index_literal(),
     demo_assume_literal_dot_observe(),
+    demo_assume_literal_observe(),
     demo_assume_submodel_observe_index_literal(),
     demo_dot_assume_observe_submodel(),
     demo_dot_assume_dot_observe_matrix(),