Add failing tests for #5755

test/integration/expression-tests/coalesce/argument-type-mismatch/test.json

@@ -0,0 +1,17 @@
+{
+  "propertySpec": {"type": "string"},
+  "expression": [
+    "coalesce",
+    ["get", "a"],
+    5
+  ],
+  "expected": {
+    "compiled": {
+      "result": "error",
+      "errors": [{
+        "key": "[2]",
+        "error": "Expected string but found number instead."
+      }]
+    }
+  }
+}

test/integration/expression-tests/coalesce/inference/test.json

@@ -0,0 +1,28 @@
+{
+  "propertySpec": {"type": "string"},
+  "expression": [
+    "coalesce",
+    ["get", "a"],
+    ["get", "b"]
+  ],
+  "inputs": [
+    [{}, {"properties": {"a": "one"}}],
+    [{}, {"properties": {"b": "two"}}],
+    [{}, {"properties": {"b": 5}}],
+    [{}, {"properties": {}}]
+  ],
+  "expected": {
+    "compiled": {
+      "isFeatureConstant": false,
+      "isZoomConstant": true,
+      "result": "success",
+      "type": "string"
+    },
+    "outputs": [
+      "one",
+      "two",
+      {"error": "Expected value to be of type string, but found number instead."},
+      {"error": "Expected value to be of type string, but found null instead."}
+    ]
+  }
+}