deprecate node <8

Signed-off-by: Tobias Gurtzick <magic@wizardtales.com>

.travis.yml

@@ -1,7 +1,6 @@
 language: node_js
 
 node_js:
-  - 6
   - 8
   - 10
   - node

lib/learn.js

@@ -2,7 +2,8 @@ const Promise = require('bluebird');
 const Shadow = require('./driver/shadow');
 
 class STD {
-  constructor ({ schema, modSchema: mod }) {
+  constructor ({ schema, modSchema: mod }, driver) {
+    this.driver = driver;
     this.indizies = schema.i;
     this.schema = schema.c;
     this.foreign = schema.f;
@@ -93,9 +94,22 @@ class STD {
     return this.createTable.apply(this, args);
   }
 
-  removeColumn (t, c) {
+  removeColumn (t, c, o) {
     let alter = {};
     if (this.schema[t]) {
+      if (this.schema[t][c].notNull === true) {
+        if (this.driver._meta.supports.optionParam === true) {
+          throw new Error(
+            'Can not drop a notNull column without providing a' +
+              ' recreation strategy.'
+          );
+        } else {
+          throw new Error(
+            'This driver does not support optionParameters which are' +
+              ' required to provide a recreation strategy.'
+          );
+        }
+      }
       this.modS[t] = {};
       this.modS[t][c] = this.schema[t][c];
       delete this.schema[t][c];
@@ -265,14 +279,14 @@ const noLearnError = prop => {
 module.exports = {
   getInterface: (context, file, driver, internals) => {
     if (context.learnable) {
-      const _std = new STD(internals);
+      const _std = new STD(internals, context);
       return Shadow.overshadow(
         driver,
         Object.assign(_std, context.learnable),
         noLearnError
       );
     }
 
-    return Shadow.overshadow(driver, new STD(internals), noLearnError);
+    return Shadow.overshadow(driver, new STD(internals, context), noLearnError);
   }
 };