problem: eth_getBlockByNumber("latest", ...) fails with error

fix: #20

src/test/groovy/io/emeraldpay/dshackle/test/EthereumHeadMock.groovy

@@ -62,4 +62,9 @@ class EthereumHeadMock implements Head {
     void onBeforeBlock(@NotNull Runnable handler) {
         handlers.add(handler)
     }
+
+    @Override
+    Long getCurrentHeight() {
+        return latest?.height
+    }
 }

src/test/groovy/io/emeraldpay/dshackle/test/TestingCommons.groovy

@@ -21,6 +21,8 @@ import io.emeraldpay.dshackle.FileResolver
 import io.emeraldpay.dshackle.cache.Caches
 import io.emeraldpay.dshackle.cache.CachesFactory
 import io.emeraldpay.dshackle.config.CacheConfig
+import io.emeraldpay.dshackle.data.BlockContainer
+import io.emeraldpay.dshackle.data.BlockId
 import io.emeraldpay.dshackle.reader.EmptyReader
 import io.emeraldpay.dshackle.reader.Reader
 import io.emeraldpay.dshackle.upstream.Multistream
@@ -30,12 +32,17 @@ import io.emeraldpay.dshackle.upstream.ethereum.EthereumUpstream
 import io.emeraldpay.dshackle.upstream.rpcclient.JsonRpcRequest
 import io.emeraldpay.dshackle.upstream.rpcclient.JsonRpcResponse
 import io.emeraldpay.grpc.Chain
+import io.infinitape.etherjar.domain.BlockHash
+import io.infinitape.etherjar.rpc.json.BlockJson
+
+import java.time.Instant
 
 class TestingCommons {
 
     static EthereumApiMock api() {
         return new EthereumApiMock()
     }
+
     static EthereumUpstreamMock upstream(Reader<JsonRpcRequest, JsonRpcResponse> api) {
         return new EthereumUpstreamMock(Chain.ETHEREUM, api)
     }
@@ -69,4 +76,15 @@ class TestingCommons {
     static FileResolver fileResolver() {
         return new FileResolver(new File("src/test/resources"))
     }
+
+    static BlockContainer blockForEthereum(Long height) {
+        BlockJson block = new BlockJson().tap {
+            setNumber(height)
+            setHash(BlockHash.from("0xc4b01774e426325b50f0c709753ec7cf1f1774439d587dfb91f2a4eeb8179cde"))
+            setTotalDifficulty(BigInteger.ONE)
+            setTimestamp(Instant.now())
+        }
+        return BlockContainer.from(block)
+    }
+
 }

src/test/groovy/io/emeraldpay/dshackle/upstream/ethereum/NativeCallRouterSpec.groovy

@@ -1,11 +1,18 @@
 package io.emeraldpay.dshackle.upstream.ethereum
 
+import io.emeraldpay.dshackle.Global
 import io.emeraldpay.dshackle.cache.Caches
+import io.emeraldpay.dshackle.reader.EmptyReader
 import io.emeraldpay.dshackle.test.TestingCommons
+import io.emeraldpay.dshackle.upstream.EmptyHead
+import io.emeraldpay.dshackle.upstream.Head
 import io.emeraldpay.dshackle.upstream.calls.DefaultEthereumMethods
 import io.emeraldpay.dshackle.upstream.rpcclient.JsonRpcRequest
+import io.emeraldpay.dshackle.reader.Reader
 import io.emeraldpay.grpc.Chain
+import io.infinitape.etherjar.rpc.json.BlockJson
 import org.apache.commons.collections4.functors.ConstantFactory
+import reactor.core.publisher.Mono
 import spock.lang.Specification
 
 import java.time.Duration
@@ -21,11 +28,92 @@ class NativeCallRouterSpec extends Specification {
                         Caches.default(),
                         ConstantFactory.constantFactory(new DefaultEthereumMethods(Chain.ETHEREUM))
                 ),
-                methods
+                methods,
+                new EmptyHead()
         )
         when:
         def act = router.read(new JsonRpcRequest("eth_coinbase", [])).block(Duration.ofSeconds(1))
         then:
         act.resultAsProcessedString == "0x0000000000000000000000000000000000000000"
     }
+
+    def "getBlockByNumber with latest uses latest id"() {
+        setup:
+        def head = Mock(Head) {
+            1 * getCurrentHeight() >> 101L
+        }
+        def reader = Mock(EthereumReader) {
+            _ * blocksByIdAsCont() >> new EmptyReader<>()
+            _ * txByHashAsCont() >> new EmptyReader<>()
+            1 * blocksByHeightAsCont() >> Mock(Reader) {
+                1 * read(101L) >> Mono.just(TestingCommons.blockForEthereum(101L))
+            }
+        }
+        def methods = new DefaultEthereumMethods(Chain.ETHEREUM)
+        def router = new NativeCallRouter(reader, methods, head)
+
+        when:
+        def act = router.getBlockByNumber(["latest", false])
+
+        then:
+        act != null
+        with(act.block()) {
+            it.length > 0
+            with(Global.objectMapper.readValue(it, BlockJson)) {
+                number == 101
+            }
+        }
+    }
+
+    def "getBlockByNumber with earliest uses 0 block"() {
+        setup:
+        def head = Stub(Head) {}
+        def reader = Mock(EthereumReader) {
+            _ * blocksByIdAsCont() >> new EmptyReader<>()
+            _ * txByHashAsCont() >> new EmptyReader<>()
+            1 * blocksByHeightAsCont() >> Mock(Reader) {
+                1 * read(0L) >> Mono.just(TestingCommons.blockForEthereum(0L))
+            }
+        }
+        def methods = new DefaultEthereumMethods(Chain.ETHEREUM)
+        def router = new NativeCallRouter(reader, methods, head)
+
+        when:
+        def act = router.getBlockByNumber(["earliest", false])
+
+        then:
+        act != null
+        with(act.block()) {
+            it.length > 0
+            with(Global.objectMapper.readValue(it, BlockJson)) {
+                number == 0
+            }
+        }
+    }
+
+    def "getBlockByNumber fetches the block"() {
+        setup:
+        def head = Stub(Head) {}
+        def reader = Mock(EthereumReader) {
+            _ * blocksByIdAsCont() >> new EmptyReader<>()
+            _ * txByHashAsCont() >> new EmptyReader<>()
+            1 * blocksByHeightAsCont() >> Mock(Reader) {
+                1 * read(74735L) >> Mono.just(TestingCommons.blockForEthereum(74735L))
+            }
+        }
+        def methods = new DefaultEthereumMethods(Chain.ETHEREUM)
+        def router = new NativeCallRouter(reader, methods, head)
+
+        when:
+        def act = router.getBlockByNumber(["0x123ef", false])
+
+        then:
+        act != null
+        with(act.block()) {
+            it.length > 0
+            with(Global.objectMapper.readValue(it, BlockJson)) {
+                number == 74735
+            }
+        }
+    }
 }