write test for backwards compatibility in automation report encoding …

…function (smartcontractkit#11430)

core/services/ocr2/plugins/ocr2keeper/evmregistry/v21/encoding/encoder_test.go

@@ -1,7 +1,10 @@
 package encoding
 
 import (
+	"bytes"
+	"encoding/hex"
 	"math/big"
+	"os"
 	"testing"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -12,6 +15,19 @@ import (
 	"github.com/smartcontractkit/chainlink/v2/core/services/ocr2/plugins/ocr2keeper/evmregistry/v21/core"
 )
 
+var expectedEncodedReport []byte
+
+func init() {
+	b, err := os.ReadFile("../fixtures/expected_encoded_report.txt")
+	if err != nil {
+		panic(err)
+	}
+	expectedEncodedReport, err = hex.DecodeString(string(b))
+	if err != nil {
+		panic(err)
+	}
+}
+
 func TestReportEncoder_EncodeExtract(t *testing.T) {
 	encoder := reportEncoder{
 		packer: NewAbiPacker(),
@@ -93,6 +109,25 @@ func TestReportEncoder_EncodeExtract(t *testing.T) {
 	}
 }
 
+func TestReportEncoder_BackwardsCompatibility(t *testing.T) {
+	encoder := reportEncoder{
+		packer: NewAbiPacker(),
+	}
+	results := []ocr2keepers.CheckResult{
+		newResult(1, 2, core.GenUpkeepID(ocr2keepers.LogTrigger, "10"), 5, 6),
+		newResult(3, 4, core.GenUpkeepID(ocr2keepers.ConditionTrigger, "20"), 7, 8),
+	}
+	encoded, err := encoder.Encode(results...)
+	assert.NoError(t, err)
+	if !bytes.Equal(encoded, expectedEncodedReport) {
+		assert.Fail(t,
+			"encoded report does not match expected encoded report; "+
+				"this means a breaking change has been made to the report encoding function; "+
+				"only update this test if non-backwards-compatible changes are necessary",
+		)
+	}
+}
+
 func newResult(block int64, checkBlock ocr2keepers.BlockNumber, id ocr2keepers.UpkeepIdentifier, fastGasWei, linkNative int64) ocr2keepers.CheckResult {
 	tp := core.GetUpkeepType(id)
 

core/services/ocr2/plugins/ocr2keeper/evmregistry/v21/fixtures/expected_encoded_report.txt

@@ -0,0 +1 @@
+00000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000007000000000000000000000000000000000000000000000000000000000000000800000000000000000000000000000000000000000000000000000000000000c000000000000000000000000000000000000000000000000000000000000001200000000000000000000000000000000000000000000000000000000000000180000000000000000000000000000000000000000000000000000000000000030000000000000000000000000000000000000000000000000000000000000000020100000000000000000000000000000131300000000000000000000000000000010000000000000000000000000000003230000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000064000000000000000000000000000000000000000000000000000000000000006400000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000040000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000000a0aaaaaaaa9012345678901234567890123456789012345678901234567890123412345678901234567890123456789012345678901234567890123456789012340000000000000000000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000101020304050607080102030405060708010203040506070801020304050607080000000000000000000000000000000000000000000000000000000000000040000000000000000000000000000000000000000000000000000000000000000301020304050607080102030405060708010203040506070801020304050607080000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000004000000000000000000000000000000000000000000000000000000000000000800000000000000000000000000000000000000000000000000000000000000005646174613000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000056461746130000000000000000000000000000000000000000000000000000000