kotlin: factor out db setup extension

Author: mightyguava

examples/kotlin/src/test/kotlin/com/example/authors/QueriesImplTest.kt

@@ -1,41 +1,15 @@
 package com.example.authors
 
-import org.junit.jupiter.api.AfterEach
+import com.example.dbtest.DbTestExtension
 import org.junit.jupiter.api.Assertions.assertEquals
-import org.junit.jupiter.api.BeforeEach
 import org.junit.jupiter.api.Test
-import java.nio.file.Files
-import java.nio.file.Paths
+import org.junit.jupiter.api.extension.RegisterExtension
 import java.sql.Connection
-import java.sql.DriverManager
 
-const val schema = "dinosql_test"
+class QueriesImplTest(private val conn: Connection) {
 
-class QueriesImplTest {
-    lateinit var schemaConn: Connection
-    lateinit var conn: Connection
-
-    @BeforeEach
-    fun setup() {
-        val user = System.getenv("PG_USER") ?: "postgres"
-        val pass = System.getenv("PG_PASSWORD") ?: "mysecretpassword"
-        val host = System.getenv("PG_HOST") ?: "127.0.0.1"
-        val port = System.getenv("PG_PORT") ?: "5432"
-        val db = System.getenv("PG_DATABASE") ?: "dinotest"
-        val url = "jdbc:postgresql://$host:$port/$db?user=$user&password=$pass&sslmode=disable"
-        println("db: $url")
-
-        schemaConn = DriverManager.getConnection(url)
-        schemaConn.createStatement().execute("CREATE SCHEMA $schema")
-
-        conn = DriverManager.getConnection("$url&currentSchema=$schema")
-        val stmt = Files.readString(Paths.get("src/main/resources/schema.sql"))
-        conn.createStatement().execute(stmt)
-    }
-
-    @AfterEach
-    fun teardown() {
-        schemaConn.createStatement().execute("DROP SCHEMA $schema CASCADE")
+    companion object {
+        @JvmField @RegisterExtension val db = DbTestExtension("src/main/resources/schema.sql")
     }
 
     @Test

examples/kotlin/src/test/kotlin/com/example/dbtest/DbTestExtension.kt

@@ -0,0 +1,51 @@
+package com.example.dbtest
+
+import org.junit.jupiter.api.extension.AfterEachCallback
+import org.junit.jupiter.api.extension.BeforeEachCallback
+import org.junit.jupiter.api.extension.ExtensionContext
+import org.junit.jupiter.api.extension.ParameterContext
+import org.junit.jupiter.api.extension.ParameterResolver
+import java.nio.file.Files
+import java.nio.file.Paths
+import java.sql.Connection
+import java.sql.DriverManager
+
+const val schema = "dinosql_test"
+
+class DbTestExtension(private val migrationsPath: String) : BeforeEachCallback, AfterEachCallback, ParameterResolver {
+    private val schemaConn: Connection
+    private val url: String
+
+    init {
+        val user = System.getenv("PG_USER") ?: "postgres"
+        val pass = System.getenv("PG_PASSWORD") ?: "mysecretpassword"
+        val host = System.getenv("PG_HOST") ?: "127.0.0.1"
+        val port = System.getenv("PG_PORT") ?: "5432"
+        val db = System.getenv("PG_DATABASE") ?: "dinotest"
+        url = "jdbc:postgresql://$host:$port/$db?user=$user&password=$pass&sslmode=disable"
+
+        schemaConn = DriverManager.getConnection(url)
+    }
+
+    override fun beforeEach(context: ExtensionContext) {
+        schemaConn.createStatement().execute("CREATE SCHEMA $schema")
+        val stmt = Files.readString(Paths.get(migrationsPath))
+        getConnection().createStatement().execute(stmt)
+    }
+
+    override fun afterEach(context: ExtensionContext) {
+        schemaConn.createStatement().execute("DROP SCHEMA $schema CASCADE")
+    }
+
+    private fun getConnection(): Connection {
+        return DriverManager.getConnection("$url&currentSchema=$schema")
+    }
+
+    override fun supportsParameter(parameterContext: ParameterContext, extensionContext: ExtensionContext): Boolean {
+        return parameterContext.parameter.type == Connection::class.java
+    }
+
+    override fun resolveParameter(parameterContext: ParameterContext, extensionContext: ExtensionContext): Any {
+        return getConnection()
+    }
+}