refactor: rawdb tests (#221)

## Why this should be merged

The need for examples to be in `package rawdb_test` made it difficult to
test other code that relied on non-exported `rawdb` identifiers.

## How this works

1. Move all testable examples from `database.libevm_test.go` to
`examples.libevm_test.go` _without any change_.
2. Change `database.libevm_test.go` to be in `package rawdb` and extend
the `WithSkipFreezers()` test.

## How this was tested

No change at all to testable examples. The `WithSkipFreezers()` test now
touches both the happy and (specific) error paths to demonstrate exact
behaviour (under the old approach it could have just been that there was
no error, even without the option).

Author: ARR4N

core/rawdb/database.libevm_test.go

@@ -14,200 +14,36 @@
 // along with the go-ethereum library. If not, see
 // <http://www.gnu.org/licenses/>.
 
-package rawdb_test
+package rawdb
 
 import (
-	"bytes"
-	"fmt"
-	"sort"
 	"testing"
 
-	"github.com/stretchr/testify/require"
-
-	"github.com/ava-labs/libevm/common"
-	// To ensure that all methods are available to importing packages, this test
-	// is defined in package `rawdb_test` instead of `rawdb`.
-	"github.com/ava-labs/libevm/core/rawdb"
-	"github.com/ava-labs/libevm/ethdb"
+	"github.com/stretchr/testify/assert"
 )
 
 func TestSkipFreezers(t *testing.T) {
-	require := require.New(t)
-	db := rawdb.NewMemoryDatabase()
-
-	var (
-		keyPrefix []byte
-		keyStart  []byte
-	)
-
-	require.NoError(rawdb.InspectDatabase(db, keyPrefix, keyStart, rawdb.WithSkipFreezers()))
-}
-
-// ExampleDatabaseStat demonstrates the method signatures of DatabaseStat, which
-// exposes an otherwise unexported type that won't have its methods documented.
-func ExampleDatabaseStat() {
-	var stat rawdb.DatabaseStat
-
-	stat.Add(common.StorageSize(1)) // only to demonstrate param type
-	stat.Add(2)
-
-	fmt.Println("Sum:", stat.Size())    // sum of all values passed to Add()
-	fmt.Println("Count:", stat.Count()) // number of calls to Add()
-
-	// Output:
-	// Sum: 3.00 B
-	// Count: 2
-}
-
-func ExampleInspectDatabase() {
-	db := &stubDatabase{
-		iterator: &stubIterator{
-			kvs: []keyValue{
-				// Bloom bits total = 5 + 1 = 6
-				{key: []byte("iBxxx"), value: []byte("m")},
-				// Optional stat record total = 5 + 7 = 12
-				{key: []byte("mykey"), value: []byte("myvalue")},
-				// metadata total = (13 + 7) + (14 + 7) = 41
-				{key: []byte("mymetadatakey"), value: []byte("myvalue")},
-				{key: []byte("mymetadatakey2"), value: []byte("myvalue")},
-			},
+	db := NewMemoryDatabase()
+
+	tests := []struct {
+		skipFreezers bool
+		wantErr      error
+	}{
+		{
+			skipFreezers: false,
+			wantErr:      errNotSupported,
+		},
+		{
+			skipFreezers: true,
+			wantErr:      nil,
 		},
 	}
 
-	keyPrefix := []byte(nil)
-	keyStart := []byte(nil)
-
-	var (
-		myStat rawdb.DatabaseStat
-	)
-	options := []rawdb.InspectDatabaseOption{
-		rawdb.WithDatabaseStatRecorder(func(key []byte, size common.StorageSize) bool {
-			if bytes.Equal(key, []byte("mykey")) {
-				myStat.Add(size)
-				return true
-			}
-			return false
-		}),
-		rawdb.WithDatabaseMetadataKeys(func(key []byte) bool {
-			return bytes.Equal(key, []byte("mymetadatakey"))
-		}),
-		rawdb.WithDatabaseMetadataKeys(func(key []byte) bool {
-			return bytes.Equal(key, []byte("mymetadatakey2"))
-		}),
-		rawdb.WithDatabaseStatsTransformer(func(rows [][]string) [][]string {
-			sort.Slice(rows, func(i, j int) bool {
-				ri, rj := rows[i], rows[j]
-				if ri[0] != rj[0] {
-					return ri[0] < rj[0]
-				}
-				return ri[1] < rj[1]
-			})
-
-			return append(
-				rows,
-				[]string{"My database", "My category", myStat.Size(), myStat.Count()},
-			)
-		}),
-	}
-
-	err := rawdb.InspectDatabase(db, keyPrefix, keyStart, options...)
-	if err != nil {
-		fmt.Println(err)
+	for _, tt := range tests {
+		var opts []InspectDatabaseOption
+		if tt.skipFreezers {
+			opts = append(opts, WithSkipFreezers())
+		}
+		assert.ErrorIsf(t, InspectDatabase(db, nil, nil, opts...), tt.wantErr, "InspectDatabase(%T, nil, nil, [WithSkipFreezers = %t])", db, tt.skipFreezers)
 	}
-	// Output:
-	// +-----------------------+-------------------------+---------+-------+
-	// |       DATABASE        |        CATEGORY         |  SIZE   | ITEMS |
-	// +-----------------------+-------------------------+---------+-------+
-	// | Ancient store (Chain) | Bodies                  | 0.00 B  |     0 |
-	// | Ancient store (Chain) | Diffs                   | 0.00 B  |     0 |
-	// | Ancient store (Chain) | Hashes                  | 0.00 B  |     0 |
-	// | Ancient store (Chain) | Headers                 | 0.00 B  |     0 |
-	// | Ancient store (Chain) | Receipts                | 0.00 B  |     0 |
-	// | Key-Value store       | Account snapshot        | 0.00 B  |     0 |
-	// | Key-Value store       | Beacon sync headers     | 0.00 B  |     0 |
-	// | Key-Value store       | Block hash->number      | 0.00 B  |     0 |
-	// | Key-Value store       | Block number->hash      | 0.00 B  |     0 |
-	// | Key-Value store       | Bloombit index          | 6.00 B  |     1 |
-	// | Key-Value store       | Bodies                  | 0.00 B  |     0 |
-	// | Key-Value store       | Clique snapshots        | 0.00 B  |     0 |
-	// | Key-Value store       | Contract codes          | 0.00 B  |     0 |
-	// | Key-Value store       | Difficulties            | 0.00 B  |     0 |
-	// | Key-Value store       | Hash trie nodes         | 0.00 B  |     0 |
-	// | Key-Value store       | Headers                 | 0.00 B  |     0 |
-	// | Key-Value store       | Path trie account nodes | 0.00 B  |     0 |
-	// | Key-Value store       | Path trie state lookups | 0.00 B  |     0 |
-	// | Key-Value store       | Path trie storage nodes | 0.00 B  |     0 |
-	// | Key-Value store       | Receipt lists           | 0.00 B  |     0 |
-	// | Key-Value store       | Singleton metadata      | 41.00 B |     2 |
-	// | Key-Value store       | Storage snapshot        | 0.00 B  |     0 |
-	// | Key-Value store       | Transaction index       | 0.00 B  |     0 |
-	// | Key-Value store       | Trie preimages          | 0.00 B  |     0 |
-	// | Light client          | Bloom trie nodes        | 0.00 B  |     0 |
-	// | Light client          | CHT trie nodes          | 0.00 B  |     0 |
-	// | My database           | My category             | 12.00 B |     1 |
-	// +-----------------------+-------------------------+---------+-------+
-	// |                                  TOTAL          | 59.00 B |       |
-	// +-----------------------+-------------------------+---------+-------+
-}
-
-type stubDatabase struct {
-	ethdb.Database
-	iterator ethdb.Iterator
-}
-
-func (s *stubDatabase) NewIterator(keyPrefix, keyStart []byte) ethdb.Iterator {
-	return s.iterator
-}
-
-// AncientSize is used in [InspectDatabase] to determine the ancient sizes.
-func (s *stubDatabase) AncientSize(kind string) (uint64, error) {
-	return 0, nil
-}
-
-func (s *stubDatabase) Ancients() (uint64, error) {
-	return 0, nil
-}
-
-func (s *stubDatabase) Tail() (uint64, error) {
-	return 0, nil
-}
-
-func (s *stubDatabase) Get(key []byte) ([]byte, error) {
-	return nil, nil
-}
-
-func (s *stubDatabase) ReadAncients(fn func(ethdb.AncientReaderOp) error) error {
-	return nil
-}
-
-type stubIterator struct {
-	ethdb.Iterator
-	i   int // see [stubIterator.pos]
-	kvs []keyValue
-}
-
-type keyValue struct {
-	key   []byte
-	value []byte
-}
-
-// pos returns the true iterator position, which is otherwise off by one because
-// Next() is called _before_ usage.
-func (s *stubIterator) pos() int {
-	return s.i - 1
-}
-
-func (s *stubIterator) Next() bool {
-	s.i++
-	return s.pos() < len(s.kvs)
-}
-
-func (s *stubIterator) Release() {}
-
-func (s *stubIterator) Key() []byte {
-	return s.kvs[s.pos()].key
-}
-
-func (s *stubIterator) Value() []byte {
-	return s.kvs[s.pos()].value
 }