From 3cb7bdf633d26f855d95833cf6e78996d61223aa Mon Sep 17 00:00:00 2001
From: Kael Shipman <kael.shipman@gmail.com>
Date: Fri, 21 Jan 2022 14:34:21 -0600
Subject: [PATCH] Feat: Implemented default values for undefined env vars

closes db-migrate/node-db-migrate#765

Signed-off-by: Kael Shipman <kael.shipman@gmail.com>
---
 lib/config.js                   | 31 ++++++++++++++++++++-------
 test/config_test.js             | 37 +++++++++++++++++++++++++++++++++
 test/database_with_env.json     |  4 +++-
 test/database_with_env_url.json |  2 +-
 4 files changed, 64 insertions(+), 10 deletions(-)

diff --git a/lib/config.js b/lib/config.js
index f27e641a..b0403c9c 100644
--- a/lib/config.js
+++ b/lib/config.js
@@ -96,15 +96,26 @@ exports.loadFile = function (fileName, currentEnv, plugins) {
 
 function walkConfig (level) {
   for (var configEntry in level) {
-    if (level[configEntry] && level[configEntry].ENV) {
-      if (!process.env[level[configEntry].ENV]) {
-        log.verbose(
-          'Environment variable ' + level[configEntry].ENV + ' is empty!'
-        );
+    if (!level[configEntry]) {
+      continue;
+    // If we're asking to get the value from an env var
+    } else if (level[configEntry].ENV) {
+      // If the env var is set, use it
+      if (typeof process.env[level[configEntry].ENV] !== 'undefined') {
+        level[configEntry] = process.env[level[configEntry].ENV];
+      } else {
+        // Otherwise, if a default is provided, use that
+        log.verbose('Environment variable ' + level[configEntry].ENV + ' is empty!');
+        if (typeof level[configEntry].default !== 'undefined') {
+          log.verbose('Using default value provided.');
+          level[configEntry] = level[configEntry].default;
+        } else {
+          // Otherwise, there's no var and there's no default - set it to undefined
+          level[configEntry] = undefined;
+        }
       }
-
-      level[configEntry] = process.env[level[configEntry].ENV];
-    } else if (level[configEntry] && typeof level[configEntry] === 'object') {
+    } else if (typeof level[configEntry] === 'object') {
+      // If we're NOT asking to get the value from an env var and the value is an object, recurse
       level[configEntry] = walkConfig(level[configEntry]);
     }
   }
@@ -121,6 +132,10 @@ exports.loadObject = function (_config, currentEnv) {
     if (config[env].ENV) {
       if (!process.env[config[env].ENV]) {
         log.verbose('Environment variable ' + config[env].ENV + ' is empty!');
+        if (typeof config[env].default !== 'undefined') {
+          log.verbose('Using default value provided.');
+          out[env] = parseDatabaseUrl(config[env].default);
+        }
       } else {
         out[env] = parseDatabaseUrl(process.env[config[env].ENV]);
       }
diff --git a/test/config_test.js b/test/config_test.js
index a9b5f9ee..facaaa0f 100644
--- a/test/config_test.js
+++ b/test/config_test.js
@@ -90,6 +90,10 @@ lab.experiment('config', function () {
 
     function () {
       process.env.DB_MIGRATE_TEST_VAR = 'username_from_env';
+      process.env.EMPTY_VAR = '';
+      if (typeof process.env.NOT_SET !== 'undefined') {
+        delete process.env.NOT_SET;
+      }
       var configPath = path.join(__dirname, 'database_with_env.json');
       var _config = config.load(configPath, 'prod');
 
@@ -98,6 +102,16 @@ lab.experiment('config', function () {
           Code.expect(_config.prod.username).to.equal('username_from_env');
         }
       );
+      lab.test(
+        'should load default value from not set env var', () => {
+          Code.expect(_config.prod.password).to.equal('my-password');
+        }
+      );
+      lab.test(
+        'should use value from env var even when empty, rather than default', () => {
+          Code.expect(_config.prod.host).to.equal('');
+        }
+      );
     }
   );
 
@@ -122,6 +136,29 @@ lab.experiment('config', function () {
     }
   );
 
+  lab.experiment(
+    'loading from a file from default when ENV URL is not set',
+
+    function () {
+      if (typeof process.env.DB_MIGRATE_TEST_VAR !== "undefined") {
+        delete process.env.DB_MIGRATE_TEST_VAR;
+      }
+      var configPath = path.join(__dirname, 'database_with_env_url.json');
+      var _config = config.load(configPath, 'prod');
+
+      lab.test(
+        'should load the url from default when env var not set', () => {
+          var current = _config.getCurrent();
+          Code.expect(current.settings.driver).to.equal('postgres');
+          Code.expect(current.settings.user).to.equal('uname');
+          Code.expect(current.settings.password).to.equal('pw');
+          Code.expect(current.settings.host).to.equal('server.com');
+          Code.expect(current.settings.database).to.equal('dbname');
+        }
+      );
+    }
+  );
+
   lab.experiment('loading from an URL', function () {
     var databaseUrl = 'postgres://uname:pw@server.com/dbname';
     var _config = config.loadUrl(databaseUrl, 'dev');
diff --git a/test/database_with_env.json b/test/database_with_env.json
index 6f2d5fc7..51c53683 100644
--- a/test/database_with_env.json
+++ b/test/database_with_env.json
@@ -2,6 +2,8 @@
   "prod": {
     "driver": "sqlite3",
     "filename": "prod.db",
-    "username": {"ENV": "DB_MIGRATE_TEST_VAR"}
+    "username": {"ENV": "DB_MIGRATE_TEST_VAR"},
+    "password": {"ENV": "NOT_SET", "default": "my-password"},
+    "host": {"ENV": "EMPTY_VAR", "default": "my-host"}
   }
 }
diff --git a/test/database_with_env_url.json b/test/database_with_env_url.json
index cf993432..6eafb34d 100644
--- a/test/database_with_env_url.json
+++ b/test/database_with_env_url.json
@@ -1,3 +1,3 @@
 {
-  "prod": {"ENV": "DB_MIGRATE_TEST_VAR"}
+  "prod": {"ENV": "DB_MIGRATE_TEST_VAR", "default": "postgres://uname:pw@server.com/dbname"}
 }