Added tests for the DataSource parameter

[zaleslaw]

1. Extracted the common code flows in the separate functions
2. Added support for the DataSource parameter in all methods
3. Tested the ConnectionPool functionality and its usage under the hood the typical stress-tests

Closes #1512

[AndreiKingsley]

Same, duplicating whole logic

[Copilot]

Pull Request Overview

This PR adds DataSource parameter support to all JDBC methods, refactors test code to reduce duplication, and adds connection pool stress tests using HikariCP. The changes improve code maintainability and ensure the library works correctly with connection pooling scenarios.

Key changes:

• Added HikariCP dependency and DataSource support across all JDBC read methods
• Extracted repetitive test assertions into reusable helper functions
• Added comprehensive connection pool tests to verify proper connection lifecycle management

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
gradle/libs.versions.toml	Added HikariCP version definition and library reference (upgraded from 5.1.0 to 7.0.2)
dataframe-jdbc/build.gradle.kts	Added HikariCP test dependency
dataframe-jdbc/src/test/kotlin/org/jetbrains/kotlinx/dataframe/io/h2/h2Test.kt	Refactored tests to use helper assertion functions, added DataSource initialization, and created new test cases for DataSource API and connection pooling

Comments suppressed due to low confidence (1)

gradle/libs.versions.toml:194

• There are now two library definitions for HikariCP: hikari (line 183) and hikaricp (line 194). Both point to the same artifact (com.zaxxer:HikariCP) with the same version reference. This creates unnecessary duplication. Consider keeping only one definition (preferably hikaricp since it's used in build.gradle.kts and matches the artifact name better).

hikari = { group = "com.zaxxer", name = "HikariCP", version.ref = "hikari" }
duckdb-jdbc = { group = "org.duckdb", name = "duckdb_jdbc", version.ref = "duckdb" }

exposed-core = { group = "org.jetbrains.exposed", name = "exposed-core", version.ref = "exposed" }
exposed-jdbc = { group = "org.jetbrains.exposed", name = "exposed-jdbc", version.ref = "exposed" }
exposed-kotlin-datetime = { group = "org.jetbrains.exposed", name = "exposed-kotlin-datetime", version.ref = "exposed" }
exposed-json = { group = "org.jetbrains.exposed", name = "exposed-json", version.ref = "exposed" }
exposed-money = { group = "org.jetbrains.exposed", name = "exposed-money", version.ref = "exposed" }

hibernate-core = { group = "org.hibernate.orm", name = "hibernate-core", version.ref = "hibernate" }
hibernate-hikaricp = { group = "org.hibernate.orm", name = "hibernate-hikaricp", version.ref = "hibernate" }
hikaricp = { group = "com.zaxxer", name = "HikariCP", version.ref = "hikari" }

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