More tests

src/tests/libxrpl/tx/wasm/host_context/TxNestedArrayLen.cpp

@@ -0,0 +1,76 @@
+#include <xrpl/tx/wasm/WasmCommon.h>
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+#include <tx/wasm/HostContextFixture.h>
+
+#include <cstdint>
+#include <expected>
+#include <stdexcept>
+#include <vector>
+
+namespace xrpl::test {
+
+// The engine's own rules - buffer-fit, the field cap, guest memory - are tested on the Rust
+// side, not here.
+//
+// No out region and no axis E: `getTxNestedArrayLen` answers the array's element count
+// directly rather than through a written buffer.
+struct TxNestedArrayLenCall : HostContextTest
+{
+    std::vector<std::int32_t> const steps{5, -12, 130};
+    Bytes const locatorBytes = bytesOfSteps(steps);
+};
+
+TEST_F(TxNestedArrayLenCall, LocatorBytesBecomeFieldLocatorHostReturnsCount)
+{
+    EXPECT_CALL(host, getTxNestedArrayLen(LocatorEquals(steps))).WillOnce(testing::Return(7));
+
+    EXPECT_EQ(hostContext.getTxNestedArrayLen(bytesOf(locatorBytes)), 7);
+}
+
+// `NoArray` - the field the locator resolves to is not an array - is the error this shape
+// most plausibly returns, so it stands in for axis B.
+TEST_F(TxNestedArrayLenCall, HostErrorBecomesContractReturnValue)
+{
+    EXPECT_CALL(host, getTxNestedArrayLen(LocatorEquals(steps)))
+        .WillOnce(testing::Return(std::unexpected(HostFunctionError::NoArray)));
+
+    EXPECT_EQ(
+        hostContext.getTxNestedArrayLen(bytesOf(locatorBytes)),
+        hfErrorToInt(HostFunctionError::NoArray));
+}
+
+TEST_F(TxNestedArrayLenCall, EmptyLocatorIsRefusedWithoutAskingHost)
+{
+    EXPECT_CALL(host, getTxNestedArrayLen).Times(0);
+
+    EXPECT_EQ(
+        hostContext.getTxNestedArrayLen(bytesOf(Bytes{})),
+        hfErrorToInt(HostFunctionError::LocatorMalformed));
+}
+
+// Distinct from an empty locator: `invokeWithLocator` checks the two conditions separately.
+TEST_F(TxNestedArrayLenCall, MisalignedLocatorLengthIsRefusedWithoutAskingHost)
+{
+    Bytes const oddLength{1, 2, 3};
+    EXPECT_CALL(host, getTxNestedArrayLen).Times(0);
+
+    EXPECT_EQ(
+        hostContext.getTxNestedArrayLen(bytesOf(oddLength)),
+        hfErrorToInt(HostFunctionError::LocatorMalformed));
+}
+
+TEST_F(TxNestedArrayLenCall, HostExceptionBecomesInternalFatalAndIsLogged)
+{
+    EXPECT_CALL(host, getTxNestedArrayLen(LocatorEquals(steps)))
+        .WillOnce(testing::Throw(std::runtime_error{"tx nested array len came apart"}));
+
+    EXPECT_EQ(
+        hostContext.getTxNestedArrayLen(bytesOf(locatorBytes)),
+        hfErrorToInt(HostFunctionError::InternalFatal));
+    EXPECT_THAT(logged(), testing::HasSubstr("tx nested array len came apart"));
+    EXPECT_THAT(logged(), testing::HasSubstr("getTxNestedArrayLen"));
+}
+
+}  // namespace xrpl::test