persisting repl session history

For now the history is stored in a file named “.n_repl_history” in the user’s home directory. If some day in the future a sharable default emerges, this may be changed.

References:

    tmpvar/repl.history#6
    closes #16

Author: Boris Diakur

CHANGELOG.md

@@ -1,3 +1,7 @@
+### 1.3.0 (2016-03-18)
+
+* **n_** stores its session history under `~/.n_repl_history`
+
 ### 1.2.0 (2016-03-16)
 
 * you can now enable FP mode via `$ n_ --fp`

README.md

@@ -36,7 +36,7 @@ n_ >
 
 ### FP mode
 
-It is possible to use lodash's functional programming variant `lodash/fp`:
+It is possible to use lodash’s functional programming variant `lodash/fp`:
 
 ```shell
 $ n_ --fp
@@ -61,7 +61,9 @@ $ NODE_REPL_MODE=strict n_
 n_ >
 ```
 
-__Note:__
+## Notes
+
+### Special character `_`
 
 The `_` character is special in the Node REPL (see [nodejs.org/api/repl.html](http://nodejs.org/api/repl.html#repl_repl_features)).
 **n_** redirects this special variable to `$` per default, but you can set your own using the environment variable `SPECIAL_VAR` like this:
@@ -77,4 +79,8 @@ n_ >
 
 Also note that using the command `.clear` you clear the context lodash is bound to.
 
+### History persistence
+
+**n_** stores its session history under `~/.n_repl_history`.
+
 Enjoy!

lib/n_.js

@@ -1,5 +1,9 @@
 'use strict';
 
+var osHomedir = require('os-homedir'),
+    path = require('path'),
+    replHistory = require('repl.history');
+
 // used as the special var to assign the result of REPL expressions
 var specialVar = process.env.SPECIAL_VAR || '$';
 
@@ -15,6 +19,9 @@ var repl = require('repl'),
         replMode: (process.env.NODE_REPL_MODE === 'strict' || process.argv.indexOf('--use_strict') !== -1) ? repl.REPL_MODE_STRICT : repl.REPL_MODE_MAGIC
     });
 
+// save repl history
+replHistory(server, path.join(osHomedir(), '.n_repl_history'));
+
 // create new pristine `lodash` instance
 var _ = require('lodash').runInContext(server.context);
 
@@ -57,7 +64,8 @@ _.each(repl._builtinLibs, function (name) {
 var events = server.rli._events;
 events.line = _.wrap(events.line, function (line, cmd) {
     var context = server.context;
-    line(cmd);
+    line[0](cmd); // actual command execution
+    line[1](cmd); // history persistance
     context[specialVar] = context._;
     currVal = prevVal;
 });

package.json

@@ -22,7 +22,9 @@
   ],
   "license": "MIT",
   "dependencies": {
-    "lodash": "^4.0.0"
+    "lodash": "^4.0.0",
+    "os-homedir": "^1.0.1",
+    "repl.history": "^0.1.3"
   },
   "devDependencies": {
     "coveralls": "^2.11.2",

test/test.js

@@ -2,9 +2,12 @@
 /* global describe, it */
 
 var assert = require('assert'),
+    fs = require('fs'),
     _ = require('lodash'),
     n_ = require('../lib/n_'),
     line = n_.rli._events.line,
+    osHomedir = require('os-homedir'),
+    path = require('path'),
     result = null;
 
 n_.writer = _.wrap(n_.writer, function (writer, obj) {
@@ -113,13 +116,13 @@ describe('n_', function () {
 
     describe('enabling fp mode', function () {
         it('should use lodash/fp', function (done) {
-            var previousArgv = process.argv;
             // enable fp mode
+            var previousArgv = process.argv;
             process.argv = _.concat(previousArgv, ['--fp']);
 
             // now require and setup n_ (it should now use lodash/fp)
             reset();
-            // Reset argv to previous value
+            // reset argv to previous value
             process.argv = previousArgv;
 
             line('_.map(function(v) { return v * 2; }, [1, 2, 3]);');
@@ -137,29 +140,56 @@ describe('n_', function () {
             });
             it('should throw in strict mode set via environment variable', function (done) {
                 // enable strict mode
+                var previousReplMode = process.env.NODE_REPL_MODE;
                 process.env.NODE_REPL_MODE = 'strict';
 
                 // now require and setup n_ (it should now run in strict mode)
                 reset();
+                // reset NODE_REPL_MODE to previous value
+                process.env.NODE_REPL_MODE = previousReplMode;
 
                 line('var fixed = {}; Object.preventExtensions(fixed); fixed.newProp = 1;');
                 assert.equal(result, null);
                 done();
             });
             it('should throw in strict mode set via command line option', function (done) {
-                // reset environment variab
-                process.env.NODE_REPL_MODE = undefined;
-
                 // enable strict mode
-                process.argv.push('--use_strict');
+                var previousArgv = process.argv;
+                process.argv = _.concat(previousArgv, ['--use_strict']);
 
                 // now require and setup n_ (it should now run with strict mode enabled)
                 reset();
+                // reset argv to previous value
+                process.argv = previousArgv;
 
                 line('var fixed = {}; Object.preventExtensions(fixed); fixed.newProp = 1;');
                 assert.equal(result, null);
                 done();
             });
         });
     }
+
+    describe('repl history', function () {
+        it('should save and load repl history across multiple sessions', function (done) {
+            var historyPath = path.join(osHomedir(), '.n_repl_history');
+
+            // delete any previously created history file
+            fs.unlinkSync(historyPath);
+
+            reset(); // new session
+            line('1+2');
+            reset(); // new session
+            line('null');
+            reset(); // new session
+            line('"foobar"');
+            reset(); // new session
+
+            // check history (as thoroughly as possible)
+            var historyFileContent = fs.readFileSync(historyPath, 'utf-8');
+            assert.equal(historyFileContent, ['1+2', 'null', '"foobar"', ''].join('\n'));
+            line('.load ' + historyPath);
+            assert.equal(result, 'foobar');
+            done();
+        });
+    });
 });