From 399d0cba38a3d0ba551d483627bf0b70b3f622f6 Mon Sep 17 00:00:00 2001
From: Daniel Baston <dbaston@gmail.com>
Date: Thu, 29 Aug 2024 10:03:01 -0400
Subject: [PATCH] prepare_operations: avoid crash when no rasters provided

---
 src/utils.cpp       |  4 ++++
 test/test_utils.cpp | 10 ++++++++++
 2 files changed, 14 insertions(+)

diff --git a/src/utils.cpp b/src/utils.cpp
index aeda58f..83a335d 100644
--- a/src/utils.cpp
+++ b/src/utils.cpp
@@ -342,6 +342,10 @@ prepare_operations(
   const RasterSourceVect& rasters,
   const RasterSourceVect& weights)
 {
+    if (!descriptors.empty() && rasters.empty()) {
+        throw std::runtime_error("no rasters provided to prepare_operations");
+    }
+
     std::vector<std::unique_ptr<Operation>> ops;
 
     std::vector<StatDescriptor> parsed_descriptors;
diff --git a/test/test_utils.cpp b/test/test_utils.cpp
index cb05b14..a34e9be 100644
--- a/test/test_utils.cpp
+++ b/test/test_utils.cpp
@@ -315,6 +315,16 @@ TEST_CASE("prepare_operations")
         CHECK(ops[0]->name == "mean");
         CHECK(ops[1]->name == "adj_mean");
     }
+
+    SECTION("error when no rasters are provided")
+    {
+        auto values = make_rasters("v", 0);
+        std::vector<std::unique_ptr<RasterSource>> weights;
+        std::vector<std::string> stats{ "sum" };
+
+        CHECK_THROWS_WITH(prepare_operations(stats, values, weights),
+                          Catch::Contains("no rasters provided"));
+    }
 }
 
 TEST_CASE("parsing arguments")