Ensure multiple null tables all get their values in the exposed query (#676)

Author: AlecKazakova

core/src/main/kotlin/com/alecstrong/sql/psi/core/psi/mixins/JoinClauseMixin.kt

@@ -75,6 +75,7 @@ internal abstract class JoinClauseMixin(
         rightColumns = rightColumns.map { it.copy(nullable = true) }
         rightSynthesizedColumns = rightSynthesizedColumns.map { it.copy(nullable = true) }
 
+        queryAvailable -= rightQuery
         queryAvailable += QueryResult(
           table = rightQuery.first().table,
           columns = rightColumns,
@@ -103,7 +104,7 @@ internal abstract class JoinClauseMixin(
       )
     }
 
-    return@ModifiableFileLazy queryAvailable.associateBy { it.table }.values
+    return@ModifiableFileLazy queryAvailable
   }
 
   private fun leftJoinOperator(operator: SqlJoinOperator): Boolean {

core/src/testFixtures/resources/fixtures/multiple-inner-joins/Test.s

@@ -0,0 +1,10 @@
+CREATE TABLE testTable(
+  testColumn INTEGER
+);
+
+SELECT test_column IS NOT NULL
+FROM (
+  SELECT testColumn AS test_column
+  FROM testTable
+)
+LEFT JOIN (SELECT 1);