fix(ci): satisfy Rust 1.99 clippy lints (#347)

CI tracks the moving stable toolchain, and 1.99 added/tightened lints that
fail the -D warnings clippy gate:
- must_use_candidate on six accessor methods in hyperdb-api
- assert_is_empty on assert!(x.is_empty()) in tests (use assert_eq!/assert_ne!)
- unfulfilled #[expect(clippy::float_cmp)] in hyperdb-api-core tests, which
  1.99 no longer triggers

No behaviour change.

Author: StefanSteiner

hyperdb-api-core/src/client/auth.rs

@@ -390,6 +390,6 @@ mod tests {
         let nonce1 = generate_nonce();
         let nonce2 = generate_nonce();
         assert_ne!(nonce1, nonce2);
-        assert!(!nonce1.is_empty());
+        assert_ne!(nonce1, "");
     }
 }

hyperdb-api-core/src/client/prepare.rs

@@ -692,10 +692,6 @@ mod tests {
     }
 
     #[test]
-    #[expect(
-        clippy::float_cmp,
-        reason = "1.5 is exactly representable; encode/decode must round-trip bit-for-bit"
-    )]
     fn test_sql_param_f32() {
         let encoded = 1.5_f32.encode();
         assert_eq!(encoded.len(), 4);
@@ -704,10 +700,6 @@ mod tests {
     }
 
     #[test]
-    #[expect(
-        clippy::float_cmp,
-        reason = "1.5 is exactly representable; encode/decode must round-trip bit-for-bit"
-    )]
     fn test_sql_param_f64() {
         let encoded = 1.5_f64.encode();
         assert_eq!(encoded.len(), 8);
@@ -748,7 +740,7 @@ mod tests {
     #[test]
     fn test_params_macro_empty() {
         let p = params![];
-        assert!(p.is_empty());
+        assert_eq!(p.len(), 0);
     }
 
     #[test]

hyperdb-api-core/src/protocol/copy.rs

@@ -773,7 +773,7 @@ mod tests {
         // A zero-length value is valid: 4 bytes of length prefix, no data.
         let buf = [0x00, 0x00, 0x00, 0x00];
         let bytes = read_varbinary(&buf).unwrap();
-        assert!(bytes.is_empty());
+        assert_eq!(bytes.len(), 0);
     }
 
     #[test]

hyperdb-api-core/src/protocol/types.rs

@@ -423,10 +423,6 @@ mod tests {
     }
 
     #[test]
-    #[expect(
-        clippy::float_cmp,
-        reason = "bit-for-bit round-trip through fixed-width binary encoding; epsilon compare would mask a decode regression"
-    )]
     fn test_f64_roundtrip() {
         let mut buf = BytesMut::new();
         f64_to_hyper_binary(std::f64::consts::PI, &mut buf);

hyperdb-api-core/src/types/special.rs

@@ -2182,7 +2182,7 @@ mod geo_impl {
             let wkb_geo = Geography::from_wkt("POINT(1 2)").expect("wkt to wkb");
             match wkb_geo.format().expect("format detection") {
                 GeographyFormat::Wkb(bytes) => {
-                    assert!(!bytes.is_empty());
+                    assert_ne!(bytes.len(), 0);
                     assert!(bytes[0] == 0 || bytes[0] == 1);
                 }
                 GeographyFormat::Legacy(_) => panic!("expected WKB format"),
@@ -2460,10 +2460,6 @@ mod tests {
     }
 
     #[test]
-    #[expect(
-        clippy::float_cmp,
-        reason = "42.0 is exactly representable; scale=0 conversion must be bit-exact"
-    )]
     fn test_numeric_from_binary_with_scale_zero() {
         // Unscaled value 42 with scale 0 = 42
         let mut bytes = [0u8; 16];
@@ -2571,10 +2567,6 @@ mod tests {
     }
 
     #[test]
-    #[expect(
-        clippy::float_cmp,
-        reason = "123.0 is exactly representable; scale=0 conversion must be bit-exact"
-    )]
     fn test_numeric_from_binary_with_scale_required() {
         // FromHyperBinary is intentionally NOT implemented for Numeric because
         // the scale must be obtained from type metadata - it cannot be inferred

hyperdb-api/src/grpc_connection.rs

@@ -290,6 +290,7 @@ impl GrpcConnection {
     }
 
     /// Returns the gRPC configuration.
+    #[must_use]
     pub fn config(&self) -> &GrpcConfig {
         self.client.config()
     }
@@ -425,6 +426,7 @@ impl GrpcConnectionAsync {
     }
 
     /// Returns the gRPC configuration.
+    #[must_use]
     pub fn config(&self) -> &GrpcConfig {
         self.client.config()
     }

hyperdb-api/src/inserter.rs

@@ -284,6 +284,7 @@ impl<'conn> Inserter<'conn> {
     }
 
     /// Returns the table definition.
+    #[must_use]
     pub fn table_definition(&self) -> &TableDefinition {
         &self.table_def
     }

hyperdb-api/src/names.rs

@@ -314,6 +314,7 @@ impl DatabaseName {
     }
 
     /// Returns the name component.
+    #[must_use]
     pub fn name(&self) -> &Name {
         &self.name
     }
@@ -449,6 +450,7 @@ impl SchemaName {
     }
 
     /// Returns the schema name component.
+    #[must_use]
     pub fn schema(&self) -> &Name {
         &self.schema
     }
@@ -638,6 +640,7 @@ impl TableName {
     }
 
     /// Returns the table name component.
+    #[must_use]
     pub fn table(&self) -> &Name {
         &self.table
     }
@@ -877,7 +880,7 @@ mod tests {
         let name = Name::try_new("users").unwrap();
         assert_eq!(name.to_string(), "\"users\"");
         assert_eq!(name.unescaped(), "users");
-        assert!(!name.unescaped().is_empty());
+        assert_ne!(name.unescaped(), "");
     }
 
     #[test]

hyperdb-api/tests/arrow_reader_tests.rs

@@ -56,11 +56,11 @@ fn test_arrow_reader_query() -> Result<()> {
 
     // Test query with filter
     let arrow_data = reader.query_to_arrow("SELECT * FROM products WHERE price > 15")?;
-    assert!(!arrow_data.is_empty());
+    assert_ne!(arrow_data, [] as [u8; 0]);
 
     // Test query with aggregation
     let arrow_data = reader.query_to_arrow("SELECT COUNT(*), SUM(price) FROM products")?;
-    assert!(!arrow_data.is_empty());
+    assert_ne!(arrow_data, [] as [u8; 0]);
 
     Ok(())
 }
@@ -80,7 +80,7 @@ fn test_arrow_reader_columns() -> Result<()> {
 
     // Read only specific columns
     let arrow_data = reader.table_columns_to_arrow("users", &["id", "name"])?;
-    assert!(!arrow_data.is_empty());
+    assert_ne!(arrow_data, [] as [u8; 0]);
 
     Ok(())
 }
@@ -106,7 +106,7 @@ fn test_arrow_reader_filtered() -> Result<()> {
 
     // Read with filter
     let arrow_data = reader.table_filtered_to_arrow("orders", "status = 'pending'")?;
-    assert!(!arrow_data.is_empty());
+    assert_ne!(arrow_data, [] as [u8; 0]);
 
     Ok(())
 }
@@ -161,7 +161,7 @@ fn test_arrow_reader_empty_table() -> Result<()> {
     let arrow_data = reader.table_to_arrow("empty_table")?;
 
     // Even empty result should have some data (schema at minimum)
-    assert!(!arrow_data.is_empty());
+    assert_ne!(arrow_data, [] as [u8; 0]);
 
     Ok(())
 }
@@ -192,7 +192,7 @@ fn test_arrow_reader_various_types() -> Result<()> {
 
     let reader = ArrowReader::new(&conn);
     let arrow_data = reader.table_to_arrow("typed_data")?;
-    assert!(!arrow_data.is_empty());
+    assert_ne!(arrow_data, [] as [u8; 0]);
 
     Ok(())
 }
@@ -213,7 +213,7 @@ fn test_arrow_reader_no_matching_rows() -> Result<()> {
     let arrow_data = reader.query_to_arrow("SELECT * FROM test_filter WHERE id > 100")?;
 
     // Should still have data (schema)
-    assert!(!arrow_data.is_empty());
+    assert_ne!(arrow_data, [] as [u8; 0]);
 
     Ok(())
 }
@@ -233,7 +233,7 @@ fn test_arrow_reader_schema_qualified() -> Result<()> {
 
     let reader = ArrowReader::new(&conn);
     let arrow_data = reader.table_to_arrow("custom_schema.test_table")?;
-    assert!(!arrow_data.is_empty());
+    assert_ne!(arrow_data, [] as [u8; 0]);
 
     Ok(())
 }
@@ -256,9 +256,9 @@ fn test_arrow_reader_multiple_reads() -> Result<()> {
     let data2 = reader.table_to_arrow("multi_test")?;
     let data3 = reader.query_to_arrow("SELECT COUNT(*) FROM multi_test")?;
 
-    assert!(!data1.is_empty());
-    assert!(!data2.is_empty());
-    assert!(!data3.is_empty());
+    assert_ne!(data1, [] as [u8; 0]);
+    assert_ne!(data2, [] as [u8; 0]);
+    assert_ne!(data3, [] as [u8; 0]);
 
     // Same query should return same size
     assert_eq!(data1.len(), data2.len());

hyperdb-api/tests/async_kv_store_tests.rs

@@ -71,7 +71,7 @@ async fn async_kv_full_surface() -> Result<()> {
 #[tokio::test(flavor = "current_thread")]
 async fn async_list_stores_and_validation() -> Result<()> {
     let (_hyper, conn) = fresh_async_conn("async_kv_list").await?;
-    assert!(conn.kv_list_stores().await?.is_empty());
+    assert_eq!(conn.kv_list_stores().await?, [] as [std::string::String; 0]);
     let _ = conn.kv_store("alpha").await?.set("k", "1").await?;
     let _ = conn.kv_store("beta").await?.set("k", "2").await?;
     let mut stores = conn.kv_list_stores().await?;