test more edge-cases on empty values on update

src/main/kotlin/jako/dsl/update/SetFields.kt

@@ -11,7 +11,9 @@ internal class SetFields: StatementBlock {
         return this
     }
 
-    override fun toSQL(dialect: Dialect) = if (cols.isNotEmpty()) "SET " + cols.joinToString(", ") { it.toSQL(dialect)} else ""
-    override fun params() = cols.flatMap { it.params() }
-    override fun isPresent() = cols.any { it.isPresent() }
+    override fun toSQL(dialect: Dialect) = "SET " + presentCols().joinToString(", ") { it.toSQL(dialect)}
+    override fun params() = presentCols().flatMap { it.params() }
+    override fun isPresent() = presentCols().isNotEmpty()
+
+    private fun presentCols() = cols.filter { it.isPresent() }
 }

src/main/kotlin/jako/dsl/update/Update.kt

@@ -9,7 +9,7 @@ import java.sql.Date
 import java.time.LocalDate
 
 class Update: StatementBuilder() {
-    private var table: UpdateTable? = null
+    private var table: UpdateTable = UpdateTable("")
     private val fields: SetFields = SetFields()
     private var where: Where = NoWhere()
 
@@ -37,7 +37,7 @@ class Update: StatementBuilder() {
 
     private fun fieldsOrThrow() = if(fields.isPresent()) fields else throw RuntimeException("Cannot generate update without values")
 
-    private fun updateTableOrThrow() = table ?: throw RuntimeException("Cannot generate update without table name")
+    private fun updateTableOrThrow() = if(table.isPresent()) table else throw RuntimeException("Cannot generate update without table name")
 
     companion object {
         fun table(name: String): Update {

src/test/kotlin/jako/dsl/update/UpdateTest.kt

@@ -45,12 +45,28 @@ class UpdateTest {
 
     @Test
     fun `update with where statement `() {
-        val insert = Update()
+        val update = Update()
             .table("table")
             .set("column1", 0)
             .where("column1" GT 10)
 
-        assertEquals("""UPDATE "table" SET "column1" = ? WHERE "column1" > ?""", insert.toSQL(PSQL))
-        assertEquals(listOf(0, 10), insert.params())
+        assertEquals("""UPDATE "table" SET "column1" = ? WHERE "column1" > ?""", update.toSQL(PSQL))
+        assertEquals(listOf(0, 10), update.params())
+    }
+
+    @Test
+    fun `update with empty table`() {
+        val message = assertThrows(RuntimeException::class.java) {
+            Update().table("").set("column1", 0).toSQL(PSQL)
+        }.message
+
+        assertEquals(message, "Cannot generate update without table name")
+    }
+
+    @Test
+    fun `update with empty values`() {
+        val update = Update().table("table").set("", 0).set("column1", 1)
+
+        assertEquals("""UPDATE "table" SET "column1" = ?""", update.toSQL(PSQL))
     }
 }