set new configuration item mode and make askCredential optional

Also this it moves the responsibility to throw ValidationError's from
prompt to lib/validation

constants.js

@@ -12,6 +12,23 @@ const packageInfo = require('./package.json');
  */
 const configFile = '.db-config.json';
 
+/**
+ * defines how the program must behave
+ * - automatic: the whole process happens without user intervention
+ * the program will fail if the configuration isn't full and correct
+ *
+ * - default: the selection happens without user intervention
+ * the program will ask user help if it needs some (like missing or incorrect login)
+ *
+ * manual: the program prompts the user for each possible choice
+ *
+ * @type {{automatic: string, default: string, manual: string}}
+ */
+const modes = {
+    automatic: 'automatic',
+    default: 'default',
+    manual: 'manual',
+};
 
 /**
  * Messages displayed to the user
@@ -47,6 +64,7 @@ const headers = {
 
 module.exports = {
     configFile,
+    modes,
     messages,
     headers
 };

index.js

@@ -23,9 +23,16 @@ const msg = cst.messages;
  * load configuration file, validate and clean it
  *
  * @resolves {askCredentials({dbms, host, port, user, password, schema})} configuration with any property possibly missing
+ * if mode === 'automatic', skips askCredentials and go to openSession
  */
 const getConfiguration = () => prompt.loadConfigurationFile()
-    .then(configuration => askCredentials(configuration));
+    .then((configuration) => {
+        // automatic mode doesn't askCredentials
+        if (configuration.mode !== cst.modes.automatic) {
+            return askCredentials(configuration);
+        }
+        return openSession(configuration);
+    });
 
 
 /**

lib/validation.js

@@ -5,6 +5,7 @@
 // validation framework
 const joi = require('joi');
 const db = require('./db-commons');
+const cst = require('../constants');
 
 /**
  * Validate user input against rules
@@ -21,6 +22,14 @@ const validationFromJoi = rule =>
         return true;
     };
 
+/**
+ * create a validation library for inquirer from a joi schema.
+ * the resulting object shares the same keys as the input schema but replace each joi rule with a validation method
+ * compatible with the inquirer framework
+ *
+ * @param schema joi schema to transform
+ * @return {{key: function}}
+ */
 const fromJoiToInquirer = (schema) => {
     const inquirer = {};
     Object.keys(schema).forEach((key) => {
@@ -29,7 +38,13 @@ const fromJoiToInquirer = (schema) => {
     return inquirer;
 };
 
-const subSchema = {
+/**
+ * schema for the configuration according to the joi validation framework
+ *
+ * @type {{mode, dbms, host, port, user, password, schema}}
+ */
+const schema = {
+    mode: joi.string().valid(Object.keys(cst.modes)),
     dbms: joi.string().valid(Object.keys(db.dbmsList)),
     host: joi.string().hostname(),
     port: joi.number().min(0).max(65535),
@@ -38,12 +53,39 @@ const subSchema = {
     schema: joi.string(),
 };
 
-const inquirer = fromJoiToInquirer(subSchema);
+/**
+ * validation methods usable by the prompt framework inquirer,
+ * one method for each key of the schema object
+ */
+const inquirer = fromJoiToInquirer(schema);
+
+/**
+ *
+ * @param configuration that must respect the schema
+ * also there can't be any extraneous keys
+ * if configuration.mode is 'automatic', validation will fail on absent keys
+ * @return {{mode, dbms, host, port, user, password, schema}}
+ * @throws {Error} ValidationError if the configuration doesn't satisfy the schema rules
+ * get all validationError's rather than stopping at the first one
+ */
+const validateConfiguration = (configuration) => {
+    let validator = joi.object(schema).unknown(false);
+    if (configuration.mode === cst.modes.automatic) {
+        validator = validator.requiredKeys(Object.keys(schema));
+    }
+
+    const { error, value } = validator.validate(configuration, { abortEarly: false });
+
+    if (error) {
+        throw error;
+    }
+
+    return value;
+};
 
-const configuration = joi.object(subSchema).unknown(false);
 
 module.exports = {
     validationFromJoi,
     inquirer,
-    configuration,
+    validateConfiguration,
 };

prompt.js

@@ -116,13 +116,7 @@ const loadConfigurationFile = () => fse.pathExists(cst.configFile)
         log.info(cst.messages.noConfig);
         return {};
     })
-    .then((config) => {
-        const { error, value } = validation.configuration.validate(config, { abortEarly: false });
-        if (error) {
-            throw error;
-        }
-        return value;
-    });
+    .then(config => validation.validateConfiguration(config));
 
 
 /**