test(mining): integration test against C++ testnet daemon

Build-tagged //go:build integration. Fetches a real template,
decodes it, computes header mining hash.

Co-Authored-By: Charon <charon@lethean.io>

mining/integration_test.go

@@ -0,0 +1,58 @@
+//go:build integration
+
+// Copyright (c) 2017-2026 Lethean (https://lt.hn)
+//
+// Licensed under the European Union Public Licence (EUPL) version 1.2.
+// SPDX-License-Identifier: EUPL-1.2
+
+package mining
+
+import (
+	"bytes"
+	"encoding/hex"
+	"testing"
+
+	"forge.lthn.ai/core/go-blockchain/rpc"
+	"forge.lthn.ai/core/go-blockchain/wire"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestIntegration_GetBlockTemplate(t *testing.T) {
+	client := rpc.NewClient("http://localhost:46941")
+
+	// Get daemon info to check it's running.
+	info, err := client.GetInfo()
+	require.NoError(t, err, "daemon must be running on localhost:46941")
+	t.Logf("daemon height: %d, pow_difficulty: %d", info.Height, info.PowDifficulty)
+
+	// Get a block template.
+	// Use the testnet genesis coinbase address (all zeros — won't receive real
+	// coins but the daemon accepts it for template generation).
+	tmpl, err := client.GetBlockTemplate("iTHNtestaddr")
+	if err != nil {
+		t.Skipf("getblocktemplate failed (may need valid address): %v", err)
+	}
+
+	assert.Greater(t, tmpl.Height, uint64(0))
+	assert.NotEmpty(t, tmpl.Difficulty)
+	assert.NotEmpty(t, tmpl.BlockTemplateBlob)
+
+	// Decode the template blob.
+	blobBytes, err := hex.DecodeString(tmpl.BlockTemplateBlob)
+	require.NoError(t, err)
+
+	dec := wire.NewDecoder(bytes.NewReader(blobBytes))
+	block := wire.DecodeBlock(dec)
+	require.NoError(t, dec.Err())
+
+	t.Logf("template: height=%d, major=%d, timestamp=%d, txs=%d",
+		tmpl.Height, block.MajorVersion, block.Timestamp, len(block.TxHashes))
+
+	// Compute header mining hash.
+	headerHash := HeaderMiningHash(&block)
+	t.Logf("header mining hash: %s", hex.EncodeToString(headerHash[:]))
+
+	// Verify the header hash is non-zero.
+	assert.False(t, headerHash == [32]byte{})
+}