adds constraints on valid network names and a test

zebra-chain/src/parameters/network/testnet.rs

@@ -1,5 +1,5 @@
 //! Types and implementation for Testnet consensus parameters
-use std::collections::BTreeMap;
+use std::{collections::BTreeMap, fmt};
 
 use zcash_primitives::constants as zp_constants;
 
@@ -11,6 +11,12 @@ use crate::{
     },
 };
 
+/// Reserved network names that should not be allowed for configured Testnets.
+pub const RESERVED_NETWORK_NAMES: [&str; 3] = ["Mainnet", "Testnet", "Regtest"];
+
+/// Maximum length for a configured network name.
+pub const MAX_NETWORK_NAME_LENGTH: usize = 30;
+
 /// Configurable activation heights for Regtest and configured Testnets.
 #[derive(Deserialize, Default)]
 #[serde(rename_all = "PascalCase")]
@@ -50,7 +56,7 @@ pub struct ParametersBuilder {
 impl Default for ParametersBuilder {
     fn default() -> Self {
         Self {
-            network_name: "Testnet".to_string(),
+            network_name: "UnknownTestnet".to_string(),
             // # Correctness
             //
             // `Genesis` network upgrade activation height must always be 0
@@ -73,8 +79,26 @@ impl Default for ParametersBuilder {
 
 impl ParametersBuilder {
     /// Sets the network name to be used in the [`Parameters`] being built.
-    pub fn network_name(mut self, network_name: String) -> Self {
-        self.network_name = network_name;
+    pub fn network_name(mut self, network_name: impl fmt::Display) -> Self {
+        self.network_name = network_name.to_string();
+
+        assert!(
+            !RESERVED_NETWORK_NAMES.contains(&self.network_name.as_str()),
+            "cannot use reserved network name '{network_name}' as configured Testnet name, reserved names: {RESERVED_NETWORK_NAMES:?}"
+        );
+
+        assert!(
+            self.network_name.len() <= MAX_NETWORK_NAME_LENGTH,
+            "network name {network_name} is too long, must be {MAX_NETWORK_NAME_LENGTH} characters or less"
+        );
+
+        assert!(
+            self.network_name
+                .chars()
+                .all(|x| x.is_alphanumeric() || x == '_'),
+            "network name must include only alphanumeric characters or '_'"
+        );
+
         self
     }
 
@@ -188,6 +212,7 @@ impl Default for Parameters {
     /// Returns an instance of the default public testnet [`Parameters`].
     fn default() -> Self {
         Self {
+            network_name: "Testnet".to_string(),
             activation_heights: TESTNET_ACTIVATION_HEIGHTS.iter().cloned().collect(),
             ..Self::build().finish()
         }

zebra-chain/src/parameters/network/tests/vectors.rs

@@ -5,7 +5,9 @@ use zcash_primitives::consensus::{self as zp_consensus, Parameters};
 use crate::{
     block::Height,
     parameters::{
-        testnet::{self, ConfiguredActivationHeights},
+        testnet::{
+            self, ConfiguredActivationHeights, MAX_NETWORK_NAME_LENGTH, RESERVED_NETWORK_NAMES,
+        },
         Network, NetworkUpgrade, NETWORK_UPGRADES_IN_ORDER,
     },
 };
@@ -125,3 +127,58 @@ fn activates_network_upgrades_correctly() {
         );
     }
 }
+
+/// Checks that configured testnet names are validated and used correctly.
+#[test]
+fn check_network_name() {
+    // Sets a no-op panic hook to avoid long output.
+    std::panic::set_hook(Box::new(|_| {}));
+
+    // Checks that reserved network names cannot be used for configured testnets.
+    for reserved_network_name in RESERVED_NETWORK_NAMES {
+        std::panic::catch_unwind(|| {
+            testnet::Parameters::build().network_name(reserved_network_name)
+        })
+        .expect_err("should panic when attempting to set network name as a reserved name");
+    }
+
+    // Check that max length is enforced, and that network names may only contain alphanumeric characters and '_'.
+    for invalid_network_name in [
+        "a".repeat(MAX_NETWORK_NAME_LENGTH + 1),
+        "!!!!non-alphanumeric-name".to_string(),
+    ] {
+        std::panic::catch_unwind(|| {
+            testnet::Parameters::build().network_name(invalid_network_name)
+        })
+        .expect_err("should panic when setting network name that's too long or contains non-alphanumeric characters (except '_')");
+    }
+
+    // Checks that network names are displayed correctly
+    assert_eq!(
+        Network::new_default_testnet().to_string(),
+        "Testnet",
+        "default testnet should be displayed as 'Testnet'"
+    );
+    assert_eq!(
+        Network::Mainnet.to_string(),
+        "Mainnet",
+        "Mainnet should be displayed as 'Mainnet'"
+    );
+
+    // TODO: Check Regtest
+
+    // Check that network name can contain alphanumeric characters and '_'.
+    let expected_name = "ConfiguredTestnet_1";
+    let network = testnet::Parameters::build()
+        // Check that network name can contain `MAX_NETWORK_NAME_LENGTH` characters
+        .network_name("a".repeat(MAX_NETWORK_NAME_LENGTH))
+        .network_name(expected_name)
+        .to_network();
+
+    // Check that configured network name is displayed
+    assert_eq!(
+        network.to_string(),
+        expected_name,
+        "network must be displayed as configured network name"
+    );
+}