more cleanup, unit tests

src/stan/io/stan_csv_reader.hpp

@@ -269,15 +269,15 @@ class stan_csv_reader {
   }
 
   static bool read_samples(std::istream& in, Eigen::MatrixXd& samples,
-                           stan_csv_timing& timing, std::ostream* out) {
+                           stan_csv_timing& timing) {
     std::stringstream ss;
     std::string line;
 
     int rows = 0;
     int cols = -1;
 
     if (in.peek() == '#' || in.good() == false)
-      return false;
+      return false;  // need at least one data row
 
     while (in.good()) {
       bool comment_line = (in.peek() == '#');
@@ -375,9 +375,9 @@ class stan_csv_reader {
       std::getline(in, line);  // discard variational estimate
     }
 
-    if (!read_samples(in, data.samples, data.timing, out)) {
+    if (!read_samples(in, data.samples, data.timing)) {
       if (out)
-        *out << "Warning: non-fatal error reading samples" << std::endl;
+        *out << "Unable to parse sample" << std::endl;
     }
     return data;
   }

src/test/unit/io/stan_csv_reader_test.cpp

@@ -246,7 +246,7 @@ TEST_F(StanIoStanCsvReader, read_samples1) {
   stan::io::stan_csv_timing timing;
 
   EXPECT_TRUE(stan::io::stan_csv_reader::read_samples(samples1_stream, samples,
-                                                      timing, 0));
+                                                      timing));
 
   ASSERT_EQ(5, samples.rows());
   ASSERT_EQ(55, samples.cols());
@@ -569,3 +569,23 @@ TEST_F(StanIoStanCsvReader, fixed_param) {
   fixed_param = stan::io::stan_csv_reader::parse(fixed_param_stream, &out);
   ASSERT_EQ(10, fixed_param.samples.rows());
 }
+
+
+TEST_F(StanIoStanCsvReader, no_samples) {
+  std::ifstream no_samples_stream;
+  no_samples_stream.open("src/test/unit/io/test_csv_files/bernoulli_no_samples.csv");
+  std::stringstream out;
+  stan::io::stan_csv no_samples = stan::io::stan_csv_reader::parse(no_samples_stream, &out);
+  no_samples_stream.close();
+  ASSERT_EQ(out.str(), "Unable to parse sample\n");
+}
+
+
+TEST_F(StanIoStanCsvReader, variational) {
+  std::ifstream variational_stream;
+  variational_stream.open("src/test/unit/io/test_csv_files/bernoulli_variational.csv");
+  std::stringstream out;
+  stan::io::stan_csv variational = stan::io::stan_csv_reader::parse(variational_stream, &out);
+  variational_stream.close();
+  ASSERT_EQ(1000, variational.metadata.num_samples);
+}

src/test/unit/io/test_csv_files/bernoulli_no_samples.csv

@@ -0,0 +1,57 @@
+# stan_version_major = 2
+# stan_version_minor = 35
+# stan_version_patch = 0
+# model = bernoulli_model
+# start_datetime = 2024-10-03 16:54:16 UTC
+# method = sample (Default)
+#   sample
+#     num_samples = 0
+#     num_warmup = 1000 (Default)
+#     save_warmup = false (Default)
+#     thin = 1 (Default)
+#     adapt
+#       engaged = true (Default)
+#       gamma = 0.05 (Default)
+#       delta = 0.8 (Default)
+#       kappa = 0.75 (Default)
+#       t0 = 10 (Default)
+#       init_buffer = 75 (Default)
+#       term_buffer = 50 (Default)
+#       window = 25 (Default)
+#       save_metric = false (Default)
+#     algorithm = hmc (Default)
+#       hmc
+#         engine = nuts (Default)
+#           nuts
+#             max_depth = 10 (Default)
+#         metric = diag_e (Default)
+#         metric_file =  (Default)
+#         stepsize = 1 (Default)
+#         stepsize_jitter = 0 (Default)
+#     num_chains = 1 (Default)
+# id = 1 (Default)
+# data
+#   file = examples/bernoulli/bernoulli.data.json
+# init = 2 (Default)
+# random
+#   seed = 1517767693 (Default)
+# output
+#   file = output.csv (Default)
+#   diagnostic_file =  (Default)
+#   refresh = 100 (Default)
+#   sig_figs = -1 (Default)
+#   profile_file = profile.csv (Default)
+#   save_cmdstan_config = false (Default)
+# num_threads = 1 (Default)
+# stanc_version = stanc3 v2.35.0
+# stancflags = 
+lp__,accept_stat__,stepsize__,treedepth__,n_leapfrog__,divergent__,energy__,theta
+# Adaptation terminated
+# Step size = 1.22726
+# Diagonal elements of inverse mass matrix:
+# 0.489285
+# 
+#  Elapsed Time: 0.005 seconds (Warm-up)
+#                0 seconds (Sampling)
+#                0.005 seconds (Total)
+#