Directory Restructure (#1163)

* Move tests -> testing

* Directory restructure

* Update Cargo.toml during restructure

* Update Makefile during restructure

* Fix arbitrary path

common/remote_beacon_node/src/lib.rs

@@ -0,0 +1,723 @@
+//! Provides a `RemoteBeaconNode` which interacts with a HTTP API on another Lighthouse (or
+//! compatible) instance.
+//!
+//! Presently, this is only used for testing but it _could_ become a user-facing library.
+
+use eth2_config::Eth2Config;
+use reqwest::{Client, ClientBuilder, Response, StatusCode};
+use serde::{de::DeserializeOwned, Deserialize, Serialize};
+use ssz::Encode;
+use std::marker::PhantomData;
+use std::time::Duration;
+use types::{
+    Attestation, AttestationData, AttesterSlashing, BeaconBlock, BeaconState, CommitteeIndex,
+    Epoch, EthSpec, Fork, Hash256, ProposerSlashing, PublicKey, PublicKeyBytes, Signature,
+    SignedAggregateAndProof, SignedBeaconBlock, Slot,
+};
+use url::Url;
+
+pub use operation_pool::PersistedOperationPool;
+pub use proto_array_fork_choice::core::ProtoArray;
+pub use rest_types::{
+    CanonicalHeadResponse, Committee, HeadBeaconBlock, IndividualVotesRequest,
+    IndividualVotesResponse, SyncingResponse, ValidatorDutiesRequest, ValidatorDutyBytes,
+    ValidatorRequest, ValidatorResponse, ValidatorSubscription,
+};
+
+// Setting a long timeout for debug ensures that crypto-heavy operations can still succeed.
+#[cfg(debug_assertions)]
+pub const REQUEST_TIMEOUT_SECONDS: u64 = 15;
+
+#[cfg(not(debug_assertions))]
+pub const REQUEST_TIMEOUT_SECONDS: u64 = 5;
+
+#[derive(Clone)]
+/// Connects to a remote Lighthouse (or compatible) node via HTTP.
+pub struct RemoteBeaconNode<E: EthSpec> {
+    pub http: HttpClient<E>,
+}
+
+impl<E: EthSpec> RemoteBeaconNode<E> {
+    /// Uses the default HTTP timeout.
+    pub fn new(http_endpoint: String) -> Result<Self, String> {
+        Self::new_with_timeout(http_endpoint, Duration::from_secs(REQUEST_TIMEOUT_SECONDS))
+    }
+
+    pub fn new_with_timeout(http_endpoint: String, timeout: Duration) -> Result<Self, String> {
+        Ok(Self {
+            http: HttpClient::new(http_endpoint, timeout)
+                .map_err(|e| format!("Unable to create http client: {:?}", e))?,
+        })
+    }
+}
+
+#[derive(Debug)]
+pub enum Error {
+    /// Unable to parse a URL. Check the server URL.
+    UrlParseError(url::ParseError),
+    /// The `reqwest` library returned an error.
+    ReqwestError(reqwest::Error),
+    /// There was an error when encoding/decoding an object using serde.
+    SerdeJsonError(serde_json::Error),
+    /// The server responded to the request, however it did not return a 200-type success code.
+    DidNotSucceed { status: StatusCode, body: String },
+    /// The request input was invalid.
+    InvalidInput,
+}
+
+#[derive(Clone)]
+pub struct HttpClient<E> {
+    client: Client,
+    url: Url,
+    timeout: Duration,
+    _phantom: PhantomData<E>,
+}
+
+impl<E: EthSpec> HttpClient<E> {
+    /// Creates a new instance (without connecting to the node).
+    pub fn new(server_url: String, timeout: Duration) -> Result<Self, Error> {
+        Ok(Self {
+            client: ClientBuilder::new()
+                .timeout(timeout)
+                .build()
+                .expect("should build from static configuration"),
+            url: Url::parse(&server_url)?,
+            timeout: Duration::from_secs(15),
+            _phantom: PhantomData,
+        })
+    }
+
+    pub fn beacon(&self) -> Beacon<E> {
+        Beacon(self.clone())
+    }
+
+    pub fn validator(&self) -> Validator<E> {
+        Validator(self.clone())
+    }
+
+    pub fn spec(&self) -> Spec<E> {
+        Spec(self.clone())
+    }
+
+    pub fn node(&self) -> Node<E> {
+        Node(self.clone())
+    }
+
+    pub fn advanced(&self) -> Advanced<E> {
+        Advanced(self.clone())
+    }
+
+    pub fn consensus(&self) -> Consensus<E> {
+        Consensus(self.clone())
+    }
+
+    fn url(&self, path: &str) -> Result<Url, Error> {
+        self.url.join(path).map_err(|e| e.into())
+    }
+
+    pub async fn json_post<T: Serialize>(&self, url: Url, body: T) -> Result<Response, Error> {
+        self.client
+            .post(&url.to_string())
+            .json(&body)
+            .send()
+            .await
+            .map_err(Error::from)
+    }
+
+    pub async fn json_get<T: DeserializeOwned>(
+        &self,
+        mut url: Url,
+        query_pairs: Vec<(String, String)>,
+    ) -> Result<T, Error> {
+        query_pairs.into_iter().for_each(|(key, param)| {
+            url.query_pairs_mut().append_pair(&key, &param);
+        });
+
+        let response = self
+            .client
+            .get(&url.to_string())
+            .send()
+            .await
+            .map_err(Error::from)?;
+
+        let success = error_for_status(response).await.map_err(Error::from)?;
+        success.json::<T>().await.map_err(Error::from)
+    }
+}
+
+/// Returns an `Error` (with a description) if the `response` was not a 200-type success response.
+///
+/// Distinct from `Response::error_for_status` because it includes the body of the response as
+/// text. This ensures the error message from the server is not discarded.
+async fn error_for_status(response: Response) -> Result<Response, Error> {
+    let status = response.status();
+
+    if status.is_success() {
+        return Ok(response);
+    } else {
+        let text_result = response.text().await;
+        match text_result {
+            Err(e) => Err(Error::ReqwestError(e)),
+            Ok(body) => Err(Error::DidNotSucceed { status, body }),
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum PublishStatus {
+    /// The object was valid and has been published to the network.
+    Valid,
+    /// The object was not valid and may or may not have been published to the network.
+    Invalid(String),
+    /// The server responded with an unknown status code. The object may or may not have been
+    /// published to the network.
+    Unknown,
+}
+
+impl PublishStatus {
+    /// Returns `true` if `*self == PublishStatus::Valid`.
+    pub fn is_valid(&self) -> bool {
+        *self == PublishStatus::Valid
+    }
+}
+
+/// Provides the functions on the `/validator` endpoint of the node.
+#[derive(Clone)]
+pub struct Validator<E>(HttpClient<E>);
+
+impl<E: EthSpec> Validator<E> {
+    fn url(&self, path: &str) -> Result<Url, Error> {
+        self.0
+            .url("validator/")
+            .and_then(move |url| url.join(path).map_err(Error::from))
+            .map_err(Into::into)
+    }
+
+    /// Produces an unsigned attestation.
+    pub async fn produce_attestation(
+        &self,
+        slot: Slot,
+        committee_index: CommitteeIndex,
+    ) -> Result<Attestation<E>, Error> {
+        let query_params = vec![
+            ("slot".into(), format!("{}", slot)),
+            ("committee_index".into(), format!("{}", committee_index)),
+        ];
+
+        let client = self.0.clone();
+        let url = self.url("attestation")?;
+        client.json_get(url, query_params).await
+    }
+
+    /// Produces an aggregate attestation.
+    pub async fn produce_aggregate_attestation(
+        &self,
+        attestation_data: &AttestationData,
+    ) -> Result<Attestation<E>, Error> {
+        let query_params = vec![(
+            "attestation_data".into(),
+            as_ssz_hex_string(attestation_data),
+        )];
+
+        let client = self.0.clone();
+        let url = self.url("aggregate_attestation")?;
+        client.json_get(url, query_params).await
+    }
+
+    /// Posts a list of attestations to the beacon node, expecting it to verify it and publish it to the network.
+    pub async fn publish_attestations(
+        &self,
+        attestation: Vec<Attestation<E>>,
+    ) -> Result<PublishStatus, Error> {
+        let client = self.0.clone();
+        let url = self.url("attestations")?;
+        let response = client.json_post::<_>(url, attestation).await?;
+
+        match response.status() {
+            StatusCode::OK => Ok(PublishStatus::Valid),
+            StatusCode::ACCEPTED => Ok(PublishStatus::Invalid(
+                response.text().await.map_err(Error::from)?,
+            )),
+            _ => response
+                .error_for_status()
+                .map_err(Error::from)
+                .map(|_| PublishStatus::Unknown),
+        }
+    }
+
+    /// Posts a list of signed aggregates and proofs to the beacon node, expecting it to verify it and publish it to the network.
+    pub async fn publish_aggregate_and_proof(
+        &self,
+        signed_aggregate_and_proofs: Vec<SignedAggregateAndProof<E>>,
+    ) -> Result<PublishStatus, Error> {
+        let client = self.0.clone();
+        let url = self.url("aggregate_and_proofs")?;
+        let response = client
+            .json_post::<_>(url, signed_aggregate_and_proofs)
+            .await?;
+
+        match response.status() {
+            StatusCode::OK => Ok(PublishStatus::Valid),
+            StatusCode::ACCEPTED => Ok(PublishStatus::Invalid(
+                response.text().await.map_err(Error::from)?,
+            )),
+            _ => response
+                .error_for_status()
+                .map_err(Error::from)
+                .map(|_| PublishStatus::Unknown),
+        }
+    }
+
+    /// Returns the duties required of the given validator pubkeys in the given epoch.
+    pub async fn get_duties(
+        &self,
+        epoch: Epoch,
+        validator_pubkeys: &[PublicKey],
+    ) -> Result<Vec<ValidatorDutyBytes>, Error> {
+        let client = self.0.clone();
+
+        let bulk_request = ValidatorDutiesRequest {
+            epoch,
+            pubkeys: validator_pubkeys
+                .iter()
+                .map(|pubkey| pubkey.clone().into())
+                .collect(),
+        };
+
+        let url = self.url("duties")?;
+        let response = client.json_post::<_>(url, bulk_request).await?;
+        let success = error_for_status(response).await.map_err(Error::from)?;
+        success.json().await.map_err(Error::from)
+    }
+
+    /// Posts a block to the beacon node, expecting it to verify it and publish it to the network.
+    pub async fn publish_block(&self, block: SignedBeaconBlock<E>) -> Result<PublishStatus, Error> {
+        let client = self.0.clone();
+        let url = self.url("block")?;
+        let response = client.json_post::<_>(url, block).await?;
+
+        match response.status() {
+            StatusCode::OK => Ok(PublishStatus::Valid),
+            StatusCode::ACCEPTED => Ok(PublishStatus::Invalid(
+                response.text().await.map_err(Error::from)?,
+            )),
+            _ => response
+                .error_for_status()
+                .map_err(Error::from)
+                .map(|_| PublishStatus::Unknown),
+        }
+    }
+
+    /// Requests a new (unsigned) block from the beacon node.
+    pub async fn produce_block(
+        &self,
+        slot: Slot,
+        randao_reveal: Signature,
+    ) -> Result<BeaconBlock<E>, Error> {
+        let client = self.0.clone();
+        let url = self.url("block")?;
+        client
+            .json_get::<BeaconBlock<E>>(
+                url,
+                vec![
+                    ("slot".into(), format!("{}", slot.as_u64())),
+                    ("randao_reveal".into(), as_ssz_hex_string(&randao_reveal)),
+                ],
+            )
+            .await
+    }
+
+    /// Subscribes a list of validators to particular slots for attestation production/publication.
+    pub async fn subscribe(
+        &self,
+        subscriptions: Vec<ValidatorSubscription>,
+    ) -> Result<PublishStatus, Error> {
+        let client = self.0.clone();
+        let url = self.url("subscribe")?;
+        let response = client.json_post::<_>(url, subscriptions).await?;
+
+        match response.status() {
+            StatusCode::OK => Ok(PublishStatus::Valid),
+            StatusCode::ACCEPTED => Ok(PublishStatus::Invalid(
+                response.text().await.map_err(Error::from)?,
+            )),
+            _ => response
+                .error_for_status()
+                .map_err(Error::from)
+                .map(|_| PublishStatus::Unknown),
+        }
+    }
+}
+
+/// Provides the functions on the `/beacon` endpoint of the node.
+#[derive(Clone)]
+pub struct Beacon<E>(HttpClient<E>);
+
+impl<E: EthSpec> Beacon<E> {
+    fn url(&self, path: &str) -> Result<Url, Error> {
+        self.0
+            .url("beacon/")
+            .and_then(move |url| url.join(path).map_err(Error::from))
+            .map_err(Into::into)
+    }
+
+    /// Returns the genesis time.
+    pub async fn get_genesis_time(&self) -> Result<u64, Error> {
+        let client = self.0.clone();
+        let url = self.url("genesis_time")?;
+        client.json_get(url, vec![]).await
+    }
+
+    /// Returns the genesis validators root.
+    pub async fn get_genesis_validators_root(&self) -> Result<Hash256, Error> {
+        let client = self.0.clone();
+        let url = self.url("genesis_validators_root")?;
+        client.json_get(url, vec![]).await
+    }
+
+    /// Returns the fork at the head of the beacon chain.
+    pub async fn get_fork(&self) -> Result<Fork, Error> {
+        let client = self.0.clone();
+        let url = self.url("fork")?;
+        client.json_get(url, vec![]).await
+    }
+
+    /// Returns info about the head of the canonical beacon chain.
+    pub async fn get_head(&self) -> Result<CanonicalHeadResponse, Error> {
+        let client = self.0.clone();
+        let url = self.url("head")?;
+        client.json_get::<CanonicalHeadResponse>(url, vec![]).await
+    }
+
+    /// Returns the set of known beacon chain head blocks. One of these will be the canonical head.
+    pub async fn get_heads(&self) -> Result<Vec<HeadBeaconBlock>, Error> {
+        let client = self.0.clone();
+        let url = self.url("heads")?;
+        client.json_get(url, vec![]).await
+    }
+
+    /// Returns the block and block root at the given slot.
+    pub async fn get_block_by_slot(
+        &self,
+        slot: Slot,
+    ) -> Result<(SignedBeaconBlock<E>, Hash256), Error> {
+        self.get_block("slot".to_string(), format!("{}", slot.as_u64()))
+            .await
+    }
+
+    /// Returns the block and block root at the given root.
+    pub async fn get_block_by_root(
+        &self,
+        root: Hash256,
+    ) -> Result<(SignedBeaconBlock<E>, Hash256), Error> {
+        self.get_block("root".to_string(), root_as_string(root))
+            .await
+    }
+
+    /// Returns the block and block root at the given slot.
+    async fn get_block(
+        &self,
+        query_key: String,
+        query_param: String,
+    ) -> Result<(SignedBeaconBlock<E>, Hash256), Error> {
+        let client = self.0.clone();
+        let url = self.url("block")?;
+        client
+            .json_get::<BlockResponse<E>>(url, vec![(query_key, query_param)])
+            .await
+            .map(|response| (response.beacon_block, response.root))
+    }
+
+    /// Returns the state and state root at the given slot.
+    pub async fn get_state_by_slot(&self, slot: Slot) -> Result<(BeaconState<E>, Hash256), Error> {
+        self.get_state("slot".to_string(), format!("{}", slot.as_u64()))
+            .await
+    }
+
+    /// Returns the state and state root at the given root.
+    pub async fn get_state_by_root(
+        &self,
+        root: Hash256,
+    ) -> Result<(BeaconState<E>, Hash256), Error> {
+        self.get_state("root".to_string(), root_as_string(root))
+            .await
+    }
+
+    /// Returns the root of the state at the given slot.
+    pub async fn get_state_root(&self, slot: Slot) -> Result<Hash256, Error> {
+        let client = self.0.clone();
+        let url = self.url("state_root")?;
+        client
+            .json_get(url, vec![("slot".into(), format!("{}", slot.as_u64()))])
+            .await
+    }
+
+    /// Returns the root of the block at the given slot.
+    pub async fn get_block_root(&self, slot: Slot) -> Result<Hash256, Error> {
+        let client = self.0.clone();
+        let url = self.url("block_root")?;
+        client
+            .json_get(url, vec![("slot".into(), format!("{}", slot.as_u64()))])
+            .await
+    }
+
+    /// Returns the state and state root at the given slot.
+    async fn get_state(
+        &self,
+        query_key: String,
+        query_param: String,
+    ) -> Result<(BeaconState<E>, Hash256), Error> {
+        let client = self.0.clone();
+        let url = self.url("state")?;
+        client
+            .json_get::<StateResponse<E>>(url, vec![(query_key, query_param)])
+            .await
+            .map(|response| (response.beacon_state, response.root))
+    }
+
+    /// Returns the block and block root at the given slot.
+    ///
+    /// If `state_root` is `Some`, the query will use the given state instead of the default
+    /// canonical head state.
+    pub async fn get_validators(
+        &self,
+        validator_pubkeys: Vec<PublicKey>,
+        state_root: Option<Hash256>,
+    ) -> Result<Vec<ValidatorResponse>, Error> {
+        let client = self.0.clone();
+
+        let bulk_request = ValidatorRequest {
+            state_root,
+            pubkeys: validator_pubkeys
+                .iter()
+                .map(|pubkey| pubkey.clone().into())
+                .collect(),
+        };
+
+        let url = self.url("validators")?;
+        let response = client.json_post::<_>(url, bulk_request).await?;
+        let success = error_for_status(response).await.map_err(Error::from)?;
+        success.json().await.map_err(Error::from)
+    }
+
+    /// Returns all validators.
+    ///
+    /// If `state_root` is `Some`, the query will use the given state instead of the default
+    /// canonical head state.
+    pub async fn get_all_validators(
+        &self,
+        state_root: Option<Hash256>,
+    ) -> Result<Vec<ValidatorResponse>, Error> {
+        let client = self.0.clone();
+
+        let query_params = if let Some(state_root) = state_root {
+            vec![("state_root".into(), root_as_string(state_root))]
+        } else {
+            vec![]
+        };
+
+        let url = self.url("validators/all")?;
+        client.json_get(url, query_params).await
+    }
+
+    /// Returns the active validators.
+    ///
+    /// If `state_root` is `Some`, the query will use the given state instead of the default
+    /// canonical head state.
+    pub async fn get_active_validators(
+        &self,
+        state_root: Option<Hash256>,
+    ) -> Result<Vec<ValidatorResponse>, Error> {
+        let client = self.0.clone();
+
+        let query_params = if let Some(state_root) = state_root {
+            vec![("state_root".into(), root_as_string(state_root))]
+        } else {
+            vec![]
+        };
+
+        let url = self.url("validators/active")?;
+        client.json_get(url, query_params).await
+    }
+
+    /// Returns committees at the given epoch.
+    pub async fn get_committees(&self, epoch: Epoch) -> Result<Vec<Committee>, Error> {
+        let client = self.0.clone();
+
+        let url = self.url("committees")?;
+        client
+            .json_get(url, vec![("epoch".into(), format!("{}", epoch.as_u64()))])
+            .await
+    }
+
+    pub async fn proposer_slashing(
+        &self,
+        proposer_slashing: ProposerSlashing,
+    ) -> Result<bool, Error> {
+        let client = self.0.clone();
+
+        let url = self.url("proposer_slashing")?;
+        let response = client.json_post::<_>(url, proposer_slashing).await?;
+        let success = error_for_status(response).await.map_err(Error::from)?;
+        success.json().await.map_err(Error::from)
+    }
+
+    pub async fn attester_slashing(
+        &self,
+        attester_slashing: AttesterSlashing<E>,
+    ) -> Result<bool, Error> {
+        let client = self.0.clone();
+
+        let url = self.url("attester_slashing")?;
+        let response = client.json_post::<_>(url, attester_slashing).await?;
+        let success = error_for_status(response).await.map_err(Error::from)?;
+        success.json().await.map_err(Error::from)
+    }
+}
+
+/// Provides the functions on the `/spec` endpoint of the node.
+#[derive(Clone)]
+pub struct Spec<E>(HttpClient<E>);
+
+impl<E: EthSpec> Spec<E> {
+    fn url(&self, path: &str) -> Result<Url, Error> {
+        self.0
+            .url("spec/")
+            .and_then(move |url| url.join(path).map_err(Error::from))
+            .map_err(Into::into)
+    }
+
+    pub async fn get_eth2_config(&self) -> Result<Eth2Config, Error> {
+        let client = self.0.clone();
+        let url = self.url("eth2_config")?;
+        client.json_get(url, vec![]).await
+    }
+}
+
+/// Provides the functions on the `/node` endpoint of the node.
+#[derive(Clone)]
+pub struct Node<E>(HttpClient<E>);
+
+impl<E: EthSpec> Node<E> {
+    fn url(&self, path: &str) -> Result<Url, Error> {
+        self.0
+            .url("node/")
+            .and_then(move |url| url.join(path).map_err(Error::from))
+            .map_err(Into::into)
+    }
+
+    pub async fn get_version(&self) -> Result<String, Error> {
+        let client = self.0.clone();
+        let url = self.url("version")?;
+        client.json_get(url, vec![]).await
+    }
+
+    pub async fn syncing_status(&self) -> Result<SyncingResponse, Error> {
+        let client = self.0.clone();
+        let url = self.url("syncing")?;
+        client.json_get(url, vec![]).await
+    }
+}
+
+/// Provides the functions on the `/advanced` endpoint of the node.
+#[derive(Clone)]
+pub struct Advanced<E>(HttpClient<E>);
+
+impl<E: EthSpec> Advanced<E> {
+    fn url(&self, path: &str) -> Result<Url, Error> {
+        self.0
+            .url("advanced/")
+            .and_then(move |url| url.join(path).map_err(Error::from))
+            .map_err(Into::into)
+    }
+
+    /// Gets the core `ProtoArray` struct from the node.
+    pub async fn get_fork_choice(&self) -> Result<ProtoArray, Error> {
+        let client = self.0.clone();
+        let url = self.url("fork_choice")?;
+        client.json_get(url, vec![]).await
+    }
+
+    /// Gets the core `PersistedOperationPool` struct from the node.
+    pub async fn get_operation_pool(&self) -> Result<PersistedOperationPool<E>, Error> {
+        let client = self.0.clone();
+        let url = self.url("operation_pool")?;
+        client.json_get(url, vec![]).await
+    }
+}
+
+/// Provides the functions on the `/consensus` endpoint of the node.
+#[derive(Clone)]
+pub struct Consensus<E>(HttpClient<E>);
+
+impl<E: EthSpec> Consensus<E> {
+    fn url(&self, path: &str) -> Result<Url, Error> {
+        self.0
+            .url("consensus/")
+            .and_then(move |url| url.join(path).map_err(Error::from))
+            .map_err(Into::into)
+    }
+
+    /// Gets a `IndividualVote` for each of the given `pubkeys`.
+    pub async fn get_individual_votes(
+        &self,
+        epoch: Epoch,
+        pubkeys: Vec<PublicKeyBytes>,
+    ) -> Result<IndividualVotesResponse, Error> {
+        let client = self.0.clone();
+        let req_body = IndividualVotesRequest { epoch, pubkeys };
+
+        let url = self.url("individual_votes")?;
+        let response = client.json_post::<_>(url, req_body).await?;
+        let success = error_for_status(response).await.map_err(Error::from)?;
+        success.json().await.map_err(Error::from)
+    }
+
+    /// Gets a `VoteCount` for the given `epoch`.
+    pub async fn get_vote_count(&self, epoch: Epoch) -> Result<IndividualVotesResponse, Error> {
+        let client = self.0.clone();
+        let query_params = vec![("epoch".into(), format!("{}", epoch.as_u64()))];
+        let url = self.url("vote_count")?;
+        client.json_get(url, query_params).await
+    }
+}
+
+#[derive(Deserialize)]
+#[serde(bound = "T: EthSpec")]
+pub struct BlockResponse<T: EthSpec> {
+    pub beacon_block: SignedBeaconBlock<T>,
+    pub root: Hash256,
+}
+
+#[derive(Deserialize)]
+#[serde(bound = "T: EthSpec")]
+pub struct StateResponse<T: EthSpec> {
+    pub beacon_state: BeaconState<T>,
+    pub root: Hash256,
+}
+
+fn root_as_string(root: Hash256) -> String {
+    format!("0x{:?}", root)
+}
+
+fn as_ssz_hex_string<T: Encode>(item: &T) -> String {
+    format!("0x{}", hex::encode(item.as_ssz_bytes()))
+}
+
+impl From<reqwest::Error> for Error {
+    fn from(e: reqwest::Error) -> Error {
+        Error::ReqwestError(e)
+    }
+}
+
+impl From<url::ParseError> for Error {
+    fn from(e: url::ParseError) -> Error {
+        Error::UrlParseError(e)
+    }
+}
+
+impl From<serde_json::Error> for Error {
+    fn from(e: serde_json::Error) -> Error {
+        Error::SerdeJsonError(e)
+    }
+}