Add plugin support in QInstanceValidator, with first implementation being BasepullExtractStepValidator

qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/instances/QInstanceValidator.java

@@ -24,8 +24,10 @@ package com.kingsrook.qqq.backend.core.instances;
 
 import java.io.Serializable;
 import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.List;
@@ -43,6 +45,7 @@ import com.kingsrook.qqq.backend.core.actions.processes.BackendStep;
 import com.kingsrook.qqq.backend.core.actions.scripts.TestScriptActionInterface;
 import com.kingsrook.qqq.backend.core.actions.values.QCustomPossibleValueProvider;
 import com.kingsrook.qqq.backend.core.exceptions.QInstanceValidationException;
+import com.kingsrook.qqq.backend.core.instances.validation.plugins.QInstanceValidatorPluginInterface;
 import com.kingsrook.qqq.backend.core.logging.QLogger;
 import com.kingsrook.qqq.backend.core.model.actions.tables.query.QFilterCriteria;
 import com.kingsrook.qqq.backend.core.model.actions.tables.query.QFilterOrderBy;
@@ -52,9 +55,11 @@ import com.kingsrook.qqq.backend.core.model.metadata.QBackendMetaData;
 import com.kingsrook.qqq.backend.core.model.metadata.QInstance;
 import com.kingsrook.qqq.backend.core.model.metadata.QSupplementalInstanceMetaData;
 import com.kingsrook.qqq.backend.core.model.metadata.authentication.QAuthenticationMetaData;
+import com.kingsrook.qqq.backend.core.model.metadata.automation.QAutomationProviderMetaData;
 import com.kingsrook.qqq.backend.core.model.metadata.code.QCodeReference;
 import com.kingsrook.qqq.backend.core.model.metadata.code.QCodeType;
 import com.kingsrook.qqq.backend.core.model.metadata.dashboard.ParentWidgetMetaData;
+import com.kingsrook.qqq.backend.core.model.metadata.dashboard.QWidgetMetaDataInterface;
 import com.kingsrook.qqq.backend.core.model.metadata.fields.AdornmentType;
 import com.kingsrook.qqq.backend.core.model.metadata.fields.FieldAdornment;
 import com.kingsrook.qqq.backend.core.model.metadata.fields.QFieldMetaData;
@@ -64,16 +69,21 @@ import com.kingsrook.qqq.backend.core.model.metadata.joins.QJoinMetaData;
 import com.kingsrook.qqq.backend.core.model.metadata.layout.QAppChildMetaData;
 import com.kingsrook.qqq.backend.core.model.metadata.layout.QAppMetaData;
 import com.kingsrook.qqq.backend.core.model.metadata.layout.QAppSection;
+import com.kingsrook.qqq.backend.core.model.metadata.possiblevalues.QPossibleValueSource;
 import com.kingsrook.qqq.backend.core.model.metadata.processes.QBackendStepMetaData;
 import com.kingsrook.qqq.backend.core.model.metadata.processes.QProcessMetaData;
 import com.kingsrook.qqq.backend.core.model.metadata.processes.QStepMetaData;
 import com.kingsrook.qqq.backend.core.model.metadata.processes.QSupplementalProcessMetaData;
+import com.kingsrook.qqq.backend.core.model.metadata.queues.QQueueMetaData;
+import com.kingsrook.qqq.backend.core.model.metadata.queues.QQueueProviderMetaData;
 import com.kingsrook.qqq.backend.core.model.metadata.queues.SQSQueueProviderMetaData;
 import com.kingsrook.qqq.backend.core.model.metadata.reporting.QReportDataSource;
 import com.kingsrook.qqq.backend.core.model.metadata.reporting.QReportField;
+import com.kingsrook.qqq.backend.core.model.metadata.reporting.QReportMetaData;
 import com.kingsrook.qqq.backend.core.model.metadata.reporting.QReportView;
 import com.kingsrook.qqq.backend.core.model.metadata.scheduleing.QScheduleMetaData;
 import com.kingsrook.qqq.backend.core.model.metadata.security.FieldSecurityLock;
+import com.kingsrook.qqq.backend.core.model.metadata.security.QSecurityKeyType;
 import com.kingsrook.qqq.backend.core.model.metadata.security.RecordSecurityLock;
 import com.kingsrook.qqq.backend.core.model.metadata.tables.AssociatedScript;
 import com.kingsrook.qqq.backend.core.model.metadata.tables.Association;
@@ -90,6 +100,7 @@ import com.kingsrook.qqq.backend.core.model.metadata.tables.cache.CacheOf;
 import com.kingsrook.qqq.backend.core.model.metadata.tables.cache.CacheUseCase;
 import com.kingsrook.qqq.backend.core.modules.authentication.QAuthenticationModuleCustomizerInterface;
 import com.kingsrook.qqq.backend.core.utils.CollectionUtils;
+import com.kingsrook.qqq.backend.core.utils.ListingHash;
 import com.kingsrook.qqq.backend.core.utils.StringUtils;
 import com.kingsrook.qqq.backend.core.utils.ValueUtils;
 import com.kingsrook.qqq.backend.core.utils.lambdas.UnsafeLambda;
@@ -111,6 +122,8 @@ public class QInstanceValidator
 
    private boolean printWarnings = false;
 
+   private static ListingHash<Class<?>, QInstanceValidatorPluginInterface<?>> validatorPlugins = new ListingHash<>();
+
    private List<String> errors = new ArrayList<>();
 
 
@@ -171,6 +184,8 @@ public class QInstanceValidator
          validateSupplementalMetaData(qInstance);
 
          validateUniqueTopLevelNames(qInstance);
+
+         runPlugins(QInstance.class, qInstance, qInstance);
       }
       catch(Exception e)
       {
@@ -189,6 +204,57 @@ public class QInstanceValidator
 
 
 
+   /*******************************************************************************
+    **
+    *******************************************************************************/
+   public static void addValidatorPlugin(QInstanceValidatorPluginInterface<?> plugin)
+   {
+      Optional<Method> validateMethod = Arrays.stream(plugin.getClass().getDeclaredMethods())
+         .filter(m -> m.getName().equals("validate")
+            && m.getParameterCount() == 3
+            && !m.getParameterTypes()[0].equals(Object.class)
+            && m.getParameterTypes()[1].equals(QInstance.class)
+            && m.getParameterTypes()[2].equals(QInstanceValidator.class)
+         ).findFirst();
+
+      if(validateMethod.isPresent())
+      {
+         Class<?> parameterType = validateMethod.get().getParameterTypes()[0];
+         validatorPlugins.add(parameterType, plugin);
+      }
+      else
+      {
+         LOG.warn("Could not find validate method on validator plugin [" + plugin.getClass().getName() + "] (to infer type being validated) - this plugin will not be used.");
+      }
+   }
+
+
+
+   /*******************************************************************************
+    **
+    *******************************************************************************/
+   public static void removeAllValidatorPlugins()
+   {
+      validatorPlugins.clear();
+   }
+
+
+
+   /*******************************************************************************
+    **
+    *******************************************************************************/
+   private <T> void runPlugins(Class<T> c, T t, QInstance qInstance)
+   {
+      for(QInstanceValidatorPluginInterface<?> plugin : CollectionUtils.nonNullList(validatorPlugins.get(c)))
+      {
+         @SuppressWarnings("unchecked")
+         QInstanceValidatorPluginInterface<T> processPlugin = (QInstanceValidatorPluginInterface<T>) plugin;
+         processPlugin.validate(t, qInstance, this);
+      }
+   }
+
+
+
    /*******************************************************************************
     **
     *******************************************************************************/
@@ -197,6 +263,8 @@ public class QInstanceValidator
       for(QSupplementalInstanceMetaData supplementalInstanceMetaData : CollectionUtils.nonNullMap(qInstance.getSupplementalMetaData()).values())
       {
          supplementalInstanceMetaData.validate(qInstance, this);
+
+         runPlugins(QSupplementalInstanceMetaData.class, supplementalInstanceMetaData, qInstance);
       }
    }
 
@@ -234,6 +302,8 @@ public class QInstanceValidator
             {
                assertCondition(qInstance.getPossibleValueSource(securityKeyType.getPossibleValueSourceName()) != null, "Unrecognized possibleValueSourceName in securityKeyType: " + name);
             }
+
+            runPlugins(QSecurityKeyType.class, securityKeyType, qInstance);
          }
       });
    }
@@ -280,6 +350,8 @@ public class QInstanceValidator
                assertNoException(() -> qInstance.getTable(join.getRightTable()).getField(orderBy.getFieldName()), "Field name " + orderBy.getFieldName() + " in orderBy for join " + joinName + " is not a defined field in the right-table " + join.getRightTable());
             }
          }
+
+         runPlugins(QJoinMetaData.class, join, qInstance);
       });
    }
 
@@ -343,6 +415,8 @@ public class QInstanceValidator
                assertCondition(StringUtils.hasContent(sqsQueueProvider.getBaseURL()), "Missing baseURL for SQSQueueProvider: " + name);
                assertCondition(StringUtils.hasContent(sqsQueueProvider.getRegion()), "Missing region for SQSQueueProvider: " + name);
             }
+
+            runPlugins(QQueueProviderMetaData.class, queueProvider, qInstance);
          });
       }
 
@@ -357,6 +431,8 @@ public class QInstanceValidator
             {
                assertCondition(qInstance.getProcesses() != null && qInstance.getProcess(queue.getProcessName()) != null, "Unrecognized processName for queue: " + name);
             }
+
+            runPlugins(QQueueMetaData.class, queue, qInstance);
          });
       }
    }
@@ -375,6 +451,8 @@ public class QInstanceValidator
             assertCondition(Objects.equals(backendName, backend.getName()), "Inconsistent naming for backend: " + backendName + "/" + backend.getName() + ".");
 
             backend.performValidation(this);
+
+            runPlugins(QBackendMetaData.class, backend, qInstance);
          });
       }
    }
@@ -392,6 +470,8 @@ public class QInstanceValidator
          {
             assertCondition(Objects.equals(name, automationProvider.getName()), "Inconsistent naming for automationProvider: " + name + "/" + automationProvider.getName() + ".");
             assertCondition(automationProvider.getType() != null, "Missing type for automationProvider: " + name);
+
+            runPlugins(QAutomationProviderMetaData.class, automationProvider, qInstance);
          });
       }
    }
@@ -410,6 +490,8 @@ public class QInstanceValidator
          {
             validateSimpleCodeReference("Instance Authentication meta data customizer ", authentication.getCustomizer(), QAuthenticationModuleCustomizerInterface.class);
          }
+
+         runPlugins(QAuthenticationMetaData.class, authentication, qInstance);
       }
    }
 
@@ -532,6 +614,8 @@ public class QInstanceValidator
             {
                supplementalTableMetaData.validate(qInstance, table, this);
             }
+
+            runPlugins(QTableMetaData.class, table, qInstance);
          });
       }
    }
@@ -1330,6 +1414,7 @@ public class QInstanceValidator
                supplementalProcessMetaData.validate(qInstance, process, this);
             }
 
+            runPlugins(QProcessMetaData.class, process, qInstance);
          });
       }
    }
@@ -1436,6 +1521,8 @@ public class QInstanceValidator
                   // view.getTitleFormat(); view.getTitleFields(); // validate these match?
                }
             }
+
+            runPlugins(QReportMetaData.class, report, qInstance);
          });
       }
    }
@@ -1556,9 +1643,9 @@ public class QInstanceValidator
                }
             }
 
-            //////////////////////////////////////////
+            ////////////////////////////////////////
-            // validate field sections in the table //
+            // validate field sections in the app //
-            //////////////////////////////////////////
+            ////////////////////////////////////////
             Set<String> childNamesInSections = new HashSet<>();
             if(app.getSections() != null)
             {
@@ -1586,6 +1673,8 @@ public class QInstanceValidator
             {
                assertCondition(qInstance.getWidget(widgetName) != null, "App " + appName + " widget " + widgetName + " is not a recognized widget.");
             }
+
+            runPlugins(QAppMetaData.class, app, qInstance);
          });
       }
    }
@@ -1618,6 +1707,8 @@ public class QInstanceValidator
                      }
                   }
                }
+
+               runPlugins(QWidgetMetaDataInterface.class, widget, qInstance);
             }
          );
       }
@@ -1703,6 +1794,8 @@ public class QInstanceValidator
                   }
                   default -> errors.add("Unexpected possibleValueSource type: " + possibleValueSource.getType());
                }
+
+               runPlugins(QPossibleValueSource.class, possibleValueSource, qInstance);
             }
          });
       }

qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/instances/validation/plugins/BasepullExtractStepValidator.java

@@ -0,0 +1,87 @@
+/*
+ * QQQ - Low-code Application Framework for Engineers.
+ * Copyright (C) 2021-2024.  Kingsrook, LLC
+ * 651 N Broad St Ste 205 # 6917 | Middletown DE 19709 | United States
+ * contact@kingsrook.com
+ * https://github.com/Kingsrook/
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.kingsrook.qqq.backend.core.instances.validation.plugins;
+
+
+import com.kingsrook.qqq.backend.core.actions.customizers.QCodeLoader;
+import com.kingsrook.qqq.backend.core.instances.QInstanceValidator;
+import com.kingsrook.qqq.backend.core.model.metadata.QInstance;
+import com.kingsrook.qqq.backend.core.model.metadata.code.QCodeReference;
+import com.kingsrook.qqq.backend.core.model.metadata.fields.QFieldMetaData;
+import com.kingsrook.qqq.backend.core.model.metadata.processes.QProcessMetaData;
+import com.kingsrook.qqq.backend.core.processes.implementations.basepull.BasepullExtractStepInterface;
+
+
+/*******************************************************************************
+ ** instance validator plugin, to ensure that a process which is a basepull uses
+ ** an extract step marked for basepulls.
+ *******************************************************************************/
+public class BasepullExtractStepValidator implements QInstanceValidatorPluginInterface<QProcessMetaData>
+{
+
+   /*******************************************************************************
+    **
+    *******************************************************************************/
+   @Override
+   public void validate(QProcessMetaData process, QInstance qInstance, QInstanceValidator qInstanceValidator)
+   {
+      ///////////////////////////////////////////////////////////////////////////
+      // if there's no basepull config on the process, don't do any validation //
+      ///////////////////////////////////////////////////////////////////////////
+      if(process.getBasepullConfiguration() == null)
+      {
+         return;
+      }
+
+      //////////////////////////////////////////////////////////////////////////////////////////
+      // try to find an input field in the process, w/ a defaultValue that's a QCodeReference //
+      // and is an instance of BasepullExtractStepInterface                                   //
+      //////////////////////////////////////////////////////////////////////////////////////////
+      boolean foundBasepullExtractStep = false;
+      for(QFieldMetaData field : process.getInputFields())
+      {
+         if(field.getDefaultValue() != null && field.getDefaultValue() instanceof QCodeReference codeReference)
+         {
+            try
+            {
+               BasepullExtractStepInterface extractStep = QCodeLoader.getAdHoc(BasepullExtractStepInterface.class, codeReference);
+               if(extractStep != null)
+               {
+                  foundBasepullExtractStep = true;
+               }
+            }
+            catch(Exception e)
+            {
+               //////////////////////////////////////////////////////
+               // ok, just means we haven't found our extract step //
+               //////////////////////////////////////////////////////
+            }
+         }
+      }
+
+      ///////////////////////////////////////////////////////////
+      // validate we could find a BasepullExtractStepInterface //
+      ///////////////////////////////////////////////////////////
+      qInstanceValidator.assertCondition(foundBasepullExtractStep, "Process [" + process.getName() + "] has a basepullConfiguration, but does not have a field with a default value that is a BasepullExtractStepInterface CodeReference");
+   }
+
+}

qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/instances/validation/plugins/QInstanceValidatorPluginInterface.java

@@ -0,0 +1,41 @@
+/*
+ * QQQ - Low-code Application Framework for Engineers.
+ * Copyright (C) 2021-2024.  Kingsrook, LLC
+ * 651 N Broad St Ste 205 # 6917 | Middletown DE 19709 | United States
+ * contact@kingsrook.com
+ * https://github.com/Kingsrook/
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.kingsrook.qqq.backend.core.instances.validation.plugins;
+
+
+import com.kingsrook.qqq.backend.core.instances.QInstanceValidator;
+import com.kingsrook.qqq.backend.core.model.metadata.QInstance;
+
+
+/*******************************************************************************
+ ** Interface for additional / optional q instance validators.  Some will be
+ ** provided by QQQ - others can be defined by applications.
+ *******************************************************************************/
+public interface QInstanceValidatorPluginInterface<T>
+{
+
+   /*******************************************************************************
+    **
+    *******************************************************************************/
+   void validate(T object, QInstance qInstance, QInstanceValidator qInstanceValidator);
+
+}

qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/processes/implementations/basepull/BasepullExtractStepInterface.java

@@ -0,0 +1,30 @@
+/*
+ * QQQ - Low-code Application Framework for Engineers.
+ * Copyright (C) 2021-2024.  Kingsrook, LLC
+ * 651 N Broad St Ste 205 # 6917 | Middletown DE 19709 | United States
+ * contact@kingsrook.com
+ * https://github.com/Kingsrook/
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.kingsrook.qqq.backend.core.processes.implementations.basepull;
+
+
+/*******************************************************************************
+ ** marker - used to indicate that a step is meant to be used  for basepull extracts.
+ *******************************************************************************/
+public interface BasepullExtractStepInterface
+{
+}

qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/processes/implementations/basepull/ExtractViaBasepullQueryStep.java

@@ -38,7 +38,7 @@ import com.kingsrook.qqq.backend.core.processes.implementations.etl.streamedwith
 /*******************************************************************************
  ** Version of ExtractViaQueryStep that knows how to set up a basepull query.
  *******************************************************************************/
-public class ExtractViaBasepullQueryStep extends ExtractViaQueryStep
+public class ExtractViaBasepullQueryStep extends ExtractViaQueryStep implements BasepullExtractStepInterface
 {
 
    /*******************************************************************************

qqq-backend-core/src/test/java/com/kingsrook/qqq/backend/core/instances/QInstanceValidatorTest.java

@@ -1,6 +1,6 @@
 /*
  * QQQ - Low-code Application Framework for Engineers.
- * Copyright (C) 2021-2022.  Kingsrook, LLC
+ * Copyright (C) 2021-2024.  Kingsrook, LLC
  * 651 N Broad St Ste 205 # 6917 | Middletown DE 19709 | United States
  * contact@kingsrook.com
  * https://github.com/Kingsrook/
@@ -38,6 +38,7 @@ import com.kingsrook.qqq.backend.core.actions.processes.BackendStep;
 import com.kingsrook.qqq.backend.core.context.QContext;
 import com.kingsrook.qqq.backend.core.exceptions.QException;
 import com.kingsrook.qqq.backend.core.exceptions.QInstanceValidationException;
+import com.kingsrook.qqq.backend.core.instances.validation.plugins.AlwaysFailsProcessValidatorPlugin;
 import com.kingsrook.qqq.backend.core.model.actions.processes.ProcessSummaryLineInterface;
 import com.kingsrook.qqq.backend.core.model.actions.processes.RunBackendStepInput;
 import com.kingsrook.qqq.backend.core.model.actions.processes.RunBackendStepOutput;
@@ -97,7 +98,7 @@ import static org.junit.jupiter.api.Assertions.fail;
  ** Unit test for QInstanceValidator.
  **
  *******************************************************************************/
-class QInstanceValidatorTest extends BaseTest
+public class QInstanceValidatorTest extends BaseTest
 {
 
    /*******************************************************************************
@@ -367,6 +368,35 @@ class QInstanceValidatorTest extends BaseTest
 
 
 
+   /*******************************************************************************
+    **
+    *******************************************************************************/
+   @Test
+   void test_validatorPlugins()
+   {
+      try
+      {
+         QInstanceValidator.addValidatorPlugin(new AlwaysFailsProcessValidatorPlugin());
+
+         ////////////////////////////////////////
+         // make sure our always failer fails. //
+         ////////////////////////////////////////
+         assertValidationFailureReasonsAllowingExtraReasons((qInstance) -> {
+         }, "always fail");
+      }
+      finally
+      {
+         QInstanceValidator.removeAllValidatorPlugins();
+         
+         ////////////////////////////////////////////////////
+         // make sure if remove all plugins, we don't fail //
+         ////////////////////////////////////////////////////
+         assertValidationSuccess((qInstance) -> {});
+      }
+   }
+
+
+
    /*******************************************************************************
     ** Test that a table with no fields fails.
     **
@@ -1949,9 +1979,9 @@ class QInstanceValidatorTest extends BaseTest
     ** failed validation with reasons that match the supplied vararg-reasons (but allow
     ** more reasons - e.g., helpful when one thing we're testing causes other errors).
     *******************************************************************************/
-   private void assertValidationFailureReasonsAllowingExtraReasons(Consumer<QInstance> setup, String... reasons)
+   public static void assertValidationFailureReasonsAllowingExtraReasons(Consumer<QInstance> setup, String... expectedReasons)
    {
-      assertValidationFailureReasons(setup, true, reasons);
+      assertValidationFailureReasons(setup, true, expectedReasons);
    }
 
 
@@ -1961,9 +1991,9 @@ class QInstanceValidatorTest extends BaseTest
     ** failed validation with reasons that match the supplied vararg-reasons (and
     ** require that exact # of reasons).
     *******************************************************************************/
-   private void assertValidationFailureReasons(Consumer<QInstance> setup, String... reasons)
+   public static void assertValidationFailureReasons(Consumer<QInstance> setup, String... expectedReasons)
    {
-      assertValidationFailureReasons(setup, false, reasons);
+      assertValidationFailureReasons(setup, false, expectedReasons);
    }
 
 
@@ -1971,7 +2001,7 @@ class QInstanceValidatorTest extends BaseTest
    /*******************************************************************************
     ** Implementation for the overloads of this name.
     *******************************************************************************/
-   private void assertValidationFailureReasons(Consumer<QInstance> setup, boolean allowExtraReasons, String... reasons)
+   public static void assertValidationFailureReasons(Consumer<QInstance> setup, boolean allowExtraReasons, String... expectedReasons)
    {
       try
       {
@@ -1982,17 +2012,27 @@ class QInstanceValidatorTest extends BaseTest
       }
       catch(QInstanceValidationException e)
       {
-         if(!allowExtraReasons)
+         assertValidationFailureReasons(allowExtraReasons, e.getReasons(), expectedReasons);
-         {
+      }
-            int noOfReasons = e.getReasons() == null ? 0 : e.getReasons().size();
+   }
-            assertEquals(reasons.length, noOfReasons, "Expected number of validation failure reasons.\nExpected reasons: " + String.join(",", reasons)
-               + "\nActual reasons: " + (noOfReasons > 0 ? String.join("\n", e.getReasons()) : "--"));
-         }
 
-         for(String reason : reasons)
+
-         {
+
-            assertReason(reason, e);
+   /*******************************************************************************
-         }
+    **
+    *******************************************************************************/
+   public static void assertValidationFailureReasons(boolean allowExtraReasons, List<String> actualReasons, String... expectedReasons)
+   {
+      if(!allowExtraReasons)
+      {
+         int noOfReasons = actualReasons == null ? 0 : actualReasons.size();
+         assertEquals(expectedReasons.length, noOfReasons, "Expected number of validation failure reasons.\nExpected reasons: " + String.join(",", expectedReasons)
+            + "\nActual reasons: " + (noOfReasons > 0 ? String.join("\n", actualReasons) : "--"));
+      }
+
+      for(String reason : expectedReasons)
+      {
+         assertReason(reason, actualReasons);
       }
    }
 
@@ -2022,11 +2062,11 @@ class QInstanceValidatorTest extends BaseTest
     ** the list of reasons in the QInstanceValidationException.
     **
     *******************************************************************************/
-   private void assertReason(String reason, QInstanceValidationException e)
+   public static void assertReason(String reason, List<String> actualReasons)
    {
-      assertNotNull(e.getReasons(), "Expected there to be a reason for the failure (but there was not)");
+      assertNotNull(actualReasons, "Expected there to be a reason for the failure (but there was not)");
-      assertThat(e.getReasons())
+      assertThat(actualReasons)
-         .withFailMessage("Expected any of:\n%s\nTo match: [%s]", e.getReasons(), reason)
+         .withFailMessage("Expected any of:\n%s\nTo match: [%s]", actualReasons, reason)
          .anyMatch(s -> s.contains(reason));
    }
 

qqq-backend-core/src/test/java/com/kingsrook/qqq/backend/core/instances/validation/plugins/AlwaysFailsProcessValidatorPlugin.java

@@ -0,0 +1,45 @@
+/*
+ * QQQ - Low-code Application Framework for Engineers.
+ * Copyright (C) 2021-2024.  Kingsrook, LLC
+ * 651 N Broad St Ste 205 # 6917 | Middletown DE 19709 | United States
+ * contact@kingsrook.com
+ * https://github.com/Kingsrook/
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.kingsrook.qqq.backend.core.instances.validation.plugins;
+
+
+import com.kingsrook.qqq.backend.core.instances.QInstanceValidator;
+import com.kingsrook.qqq.backend.core.model.metadata.QInstance;
+import com.kingsrook.qqq.backend.core.model.metadata.processes.QProcessMetaData;
+
+
+/*******************************************************************************
+ ** test instance of a validator plugin, that always adds an error
+ *******************************************************************************/
+public class AlwaysFailsProcessValidatorPlugin implements QInstanceValidatorPluginInterface<QProcessMetaData>
+{
+
+   /*******************************************************************************
+    **
+    *******************************************************************************/
+   @Override
+   public void validate(QProcessMetaData object, QInstance qInstance, QInstanceValidator qInstanceValidator)
+   {
+      qInstanceValidator.getErrors().add("I always fail.");
+   }
+
+}

qqq-backend-core/src/test/java/com/kingsrook/qqq/backend/core/instances/validation/plugins/BasepullExtractStepValidatorTest.java

@@ -0,0 +1,109 @@
+/*
+ * QQQ - Low-code Application Framework for Engineers.
+ * Copyright (C) 2021-2024.  Kingsrook, LLC
+ * 651 N Broad St Ste 205 # 6917 | Middletown DE 19709 | United States
+ * contact@kingsrook.com
+ * https://github.com/Kingsrook/
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.kingsrook.qqq.backend.core.instances.validation.plugins;
+
+
+import com.kingsrook.qqq.backend.core.BaseTest;
+import com.kingsrook.qqq.backend.core.context.QContext;
+import com.kingsrook.qqq.backend.core.instances.QInstanceValidator;
+import com.kingsrook.qqq.backend.core.model.metadata.QInstance;
+import com.kingsrook.qqq.backend.core.processes.implementations.basepull.BasepullConfiguration;
+import com.kingsrook.qqq.backend.core.processes.implementations.basepull.ExtractViaBasepullQueryStep;
+import com.kingsrook.qqq.backend.core.processes.implementations.etl.streamedwithfrontend.ExtractViaQueryStep;
+import com.kingsrook.qqq.backend.core.processes.implementations.etl.streamedwithfrontend.LoadViaInsertStep;
+import com.kingsrook.qqq.backend.core.processes.implementations.etl.streamedwithfrontend.StreamedETLWithFrontendProcess;
+import com.kingsrook.qqq.backend.core.processes.implementations.etl.streamedwithfrontend.StreamedETLWithFrontendProcessTest;
+import com.kingsrook.qqq.backend.core.utils.TestUtils;
+import org.junit.jupiter.api.Test;
+import static com.kingsrook.qqq.backend.core.instances.QInstanceValidatorTest.assertValidationFailureReasons;
+import static org.assertj.core.api.Assertions.assertThat;
+
+
+/*******************************************************************************
+ ** Unit test for BasepullExtractStepValidator 
+ *******************************************************************************/
+class BasepullExtractStepValidatorTest extends BaseTest
+{
+
+   /*******************************************************************************
+    **
+    *******************************************************************************/
+   @Test
+   void testNoExtractStepAtAllFails()
+   {
+      QInstance          qInstance = QContext.getQInstance();
+      QInstanceValidator validator = new QInstanceValidator();
+
+      ///////////////////////////////////////////////////////////////////////////////////////////////////////////
+      // turns out, our "basepullTestProcess" doesn't have an extract step, so that makes this condition fire. //
+      ///////////////////////////////////////////////////////////////////////////////////////////////////////////
+      new BasepullExtractStepValidator().validate(qInstance.getProcess(TestUtils.PROCESS_NAME_BASEPULL), qInstance, validator);
+      assertValidationFailureReasons(false, validator.getErrors(), "does not have a field with a default value that is a BasepullExtractStepInterface CodeReference");
+   }
+
+
+
+   /*******************************************************************************
+    **
+    *******************************************************************************/
+   @Test
+   void testExtractViaQueryNotBasePull()
+   {
+      QInstance          qInstance = QContext.getQInstance();
+      QInstanceValidator validator = new QInstanceValidator();
+
+      ////////////////////////////////////////////////////////////////////////////////////////////////////////////
+      // set up a streamed-etl process, but with an ExtractViaQueryStep instead of a basepull - it should fail! //
+      ////////////////////////////////////////////////////////////////////////////////////////////////////////////
+      new BasepullExtractStepValidator().validate(StreamedETLWithFrontendProcess.defineProcessMetaData(
+         TestUtils.TABLE_NAME_SHAPE,
+         TestUtils.TABLE_NAME_PERSON_MEMORY,
+         ExtractViaQueryStep.class,
+         StreamedETLWithFrontendProcessTest.TestTransformShapeToPersonStep.class,
+         LoadViaInsertStep.class).withBasepullConfiguration(new BasepullConfiguration()), qInstance, validator);
+      assertValidationFailureReasons(false, validator.getErrors(), "does not have a field with a default value that is a BasepullExtractStepInterface CodeReference");
+   }
+
+
+
+   /*******************************************************************************
+    **
+    *******************************************************************************/
+   @Test
+   void testExtractViaBasepullQueryPasses()
+   {
+      QInstance          qInstance = QContext.getQInstance();
+      QInstanceValidator validator = new QInstanceValidator();
+
+      //////////////////////////////////////////////////////////////////////////////////////////////////
+      // set up a streamed-etl process, with an ExtractViaBasepullQueryStep as expected - should pass //
+      //////////////////////////////////////////////////////////////////////////////////////////////////
+      new BasepullExtractStepValidator().validate(StreamedETLWithFrontendProcess.defineProcessMetaData(
+         TestUtils.TABLE_NAME_SHAPE,
+         TestUtils.TABLE_NAME_PERSON_MEMORY,
+         ExtractViaBasepullQueryStep.class,
+         StreamedETLWithFrontendProcessTest.TestTransformShapeToPersonStep.class,
+         LoadViaInsertStep.class).withBasepullConfiguration(new BasepullConfiguration()), qInstance, validator);
+      assertThat(validator.getErrors()).isNullOrEmpty();
+   }
+
+}