From 27563bc4e7dc7d20d1ef6acca6f7b24932cac27d Mon Sep 17 00:00:00 2001
From: Wilhelm Behncke <behncke@sitegeist.de>
Date: Thu, 3 Mar 2016 18:23:36 +0100
Subject: [PATCH] FEATURE: Make migrations tolerant towards undefined subjects

---
 src/migrations/atoms/add/index.spec.js        | 5 +++++
 src/migrations/atoms/drop/index.spec.js       | 5 +++++
 src/migrations/atoms/override/index.spec.js   | 5 +++++
 src/migrations/atoms/pop/index.spec.js        | 5 +++++
 src/migrations/atoms/remove/index.spec.js     | 5 +++++
 src/migrations/atoms/set/index.js             | 8 ++++++--
 src/migrations/atoms/set/index.spec.js        | 5 +++++
 src/migrations/atoms/shift/index.spec.js      | 5 +++++
 src/migrations/atoms/unshift/index.spec.js    | 5 +++++
 src/migrations/molecules/merge/index.spec.js  | 5 +++++
 src/migrations/molecules/toggle/index.js      | 4 ++++
 src/migrations/molecules/toggle/index.spec.js | 7 +++++++
 12 files changed, 62 insertions(+), 2 deletions(-)

diff --git a/src/migrations/atoms/add/index.spec.js b/src/migrations/atoms/add/index.spec.js
index 114ffdd..515d1bb 100644
--- a/src/migrations/atoms/add/index.spec.js
+++ b/src/migrations/atoms/add/index.spec.js
@@ -109,6 +109,11 @@ describe('Migrations > Atoms > $add', () => {
             expect(console.warn.calledOnce).to.equal(true);
             expect(console.warn.calledWith('Cannot add {a: overwrite?} to test, because it is already set.')).to.equal(true);
         });
+
+        it('should tolerate undefined subjects', () => {
+            const subject = undefined;
+            expect($add('some.path', 'someValue', subject)).to.be.an('undefined');
+        });
     });
 
     describe('Immutable', () => {
diff --git a/src/migrations/atoms/drop/index.spec.js b/src/migrations/atoms/drop/index.spec.js
index 8a67125..efa78f7 100644
--- a/src/migrations/atoms/drop/index.spec.js
+++ b/src/migrations/atoms/drop/index.spec.js
@@ -82,6 +82,11 @@ describe('Migrations > Atoms > $drop', () => {
             expect(console.warn.calledTwice).to.equal(true);
             expect(console.warn.calledWith('Cannot drop an item from a undefined.')).to.equal(true);
         });
+
+        it('should tolerate undefined subjects', () => {
+            const subject = undefined;
+            expect($drop('some.path', subject)).to.be.an('undefined');
+        });
     });
 
     describe('Immutable', () => {
diff --git a/src/migrations/atoms/override/index.spec.js b/src/migrations/atoms/override/index.spec.js
index 3747b16..0120ae4 100644
--- a/src/migrations/atoms/override/index.spec.js
+++ b/src/migrations/atoms/override/index.spec.js
@@ -70,6 +70,11 @@ describe('Migrations > Atoms > $override', () => {
             });
             expect($override('test', ['foo'], subject)).to.not.equal(subject);
         });
+
+        it('should tolerate undefined subjects', () => {
+            const subject = undefined;
+            expect($override('some.path', 'someValue', subject)).to.be.an('undefined');
+        });
     });
 
     describe('Immutable', () => {
diff --git a/src/migrations/atoms/pop/index.spec.js b/src/migrations/atoms/pop/index.spec.js
index a66c12b..1033c2b 100644
--- a/src/migrations/atoms/pop/index.spec.js
+++ b/src/migrations/atoms/pop/index.spec.js
@@ -50,6 +50,11 @@ describe('Migrations > Atoms > $pop', () => {
             expect(console.warn.calledThrice).to.equal(true);
             expect(console.warn.calledWith('Cannot pop an item from a object.')).to.equal(true);
         });
+
+        it('should tolerate undefined subjects', () => {
+            const subject = undefined;
+            expect($pop('some.path', subject)).to.be.an('undefined');
+        });
     });
 
     describe('Immutable', () => {
diff --git a/src/migrations/atoms/remove/index.spec.js b/src/migrations/atoms/remove/index.spec.js
index 734604c..80cad5c 100644
--- a/src/migrations/atoms/remove/index.spec.js
+++ b/src/migrations/atoms/remove/index.spec.js
@@ -80,6 +80,11 @@ describe('Migrations > Atoms > $remove', () => {
             expect(console.warn.calledTwice).to.equal(true);
             expect(console.warn.calledWith('Cannot remove an item from a undefined.')).to.equal(true);
         });
+
+        it('should tolerate undefined subjects', () => {
+            const subject = undefined;
+            expect($remove('some.path', 'someValue', subject)).to.be.an('undefined');
+        });
     });
 
     describe('Immutable', () => {
diff --git a/src/migrations/atoms/set/index.js b/src/migrations/atoms/set/index.js
index 460163f..ab8bfe3 100644
--- a/src/migrations/atoms/set/index.js
+++ b/src/migrations/atoms/set/index.js
@@ -40,7 +40,11 @@ const recursivelySetValueInObject = (object, value, path) => {
 //
 export default createPolymorphFunction(
     path => value => subject => {
-        const object = JSON.parse(JSON.stringify(subject));
-        return recursivelySetValueInObject(object, value, resolveObjectPath(path));
+        if (typeof subject !== 'undefined') {
+            const object = JSON.parse(JSON.stringify(subject));
+            return recursivelySetValueInObject(object, value, resolveObjectPath(path));
+        }
+
+        return subject;
     }
 );
diff --git a/src/migrations/atoms/set/index.spec.js b/src/migrations/atoms/set/index.spec.js
index d11cc63..2c47ea6 100644
--- a/src/migrations/atoms/set/index.spec.js
+++ b/src/migrations/atoms/set/index.spec.js
@@ -154,6 +154,11 @@ describe('Migrations > Atoms > $set', () => {
                 }]
             });
         });
+
+        it('should tolerate undefined subjects', () => {
+            const subject = undefined;
+            expect($set('some.path', 'someValue', subject)).to.be.an('undefined');
+        });
     });
 
     describe('Immutable', () => {
diff --git a/src/migrations/atoms/shift/index.spec.js b/src/migrations/atoms/shift/index.spec.js
index 1d7e2fb..0e18e34 100644
--- a/src/migrations/atoms/shift/index.spec.js
+++ b/src/migrations/atoms/shift/index.spec.js
@@ -50,6 +50,11 @@ describe('Migrations > Atoms > $shift', () => {
             expect(console.warn.calledThrice).to.equal(true);
             expect(console.warn.calledWith('Cannot shift an item from a object.')).to.equal(true);
         });
+
+        it('should tolerate undefined subjects', () => {
+            const subject = undefined;
+            expect($shift('some.path', subject)).to.be.an('undefined');
+        });
     });
 
     describe('Immutable', () => {
diff --git a/src/migrations/atoms/unshift/index.spec.js b/src/migrations/atoms/unshift/index.spec.js
index 648cd44..bd6a497 100644
--- a/src/migrations/atoms/unshift/index.spec.js
+++ b/src/migrations/atoms/unshift/index.spec.js
@@ -109,6 +109,11 @@ describe('Migrations > Atoms > $unshift', () => {
             expect(console.warn.calledOnce).to.equal(true);
             expect(console.warn.calledWith('Cannot add {a: overwrite?} to test, because it is already set.')).to.equal(true);
         });
+
+        it('should tolerate undefined subjects', () => {
+            const subject = undefined;
+            expect($unshift('some.path', 'someValue', subject)).to.be.an('undefined');
+        });
     });
 
     describe('Immutable', () => {
diff --git a/src/migrations/molecules/merge/index.spec.js b/src/migrations/molecules/merge/index.spec.js
index 3cadd5d..db432f5 100644
--- a/src/migrations/molecules/merge/index.spec.js
+++ b/src/migrations/molecules/merge/index.spec.js
@@ -82,6 +82,11 @@ describe('Migrations > Atoms > $merge', () => {
             });
             expect($merge('test', {a: ['foo']}, subject)).to.not.equal(subject);
         });
+
+        it('should tolerate undefined subjects', () => {
+            const subject = undefined;
+            expect($merge('some.path', {some: 'value'}, subject)).to.be.an('undefined');
+        });
     });
 
     describe('Immutable', () => {
diff --git a/src/migrations/molecules/toggle/index.js b/src/migrations/molecules/toggle/index.js
index 660a5be..490da0a 100644
--- a/src/migrations/molecules/toggle/index.js
+++ b/src/migrations/molecules/toggle/index.js
@@ -39,6 +39,8 @@ export default createPolymorphFunction(
             if (typeof target === 'boolean') {
                 return $set(path, !target, value);
             }
+        } else if (typeof value === 'undefined') {
+            return value;
         }
 
         return fallback => {
@@ -60,6 +62,8 @@ export default createPolymorphFunction(
                 // Perform value toggle with empty fallback
                 //
                 return $set(path, target === value ? getEmptyValue(value) : value, fallback);
+            } else if (typeof fallback === 'undefined') {
+                return fallback;
             }
 
             return subject => {
diff --git a/src/migrations/molecules/toggle/index.spec.js b/src/migrations/molecules/toggle/index.spec.js
index a21c283..7b240fd 100644
--- a/src/migrations/molecules/toggle/index.spec.js
+++ b/src/migrations/molecules/toggle/index.spec.js
@@ -116,6 +116,13 @@ describe('Migrations > Molecules > $toggle', () => {
             expect($toggle('test', 'foo', 'bar', subject)).to.deep.equal({ test: 'bar' });
             expect($toggle('test', 'foo', 'bar', subject)).to.not.equal(subject);
         });
+
+        it('should tolerate undefined subjects', () => {
+            const subject = undefined;
+            expect($toggle('some.path', subject)).to.be.an('undefined');
+            expect($toggle('some.path', 'foo', subject)).to.be.an('undefined');
+            expect($toggle('some.path', 'foo', 'bar', subject)).to.be.an('undefined');
+        });
     });
 
     describe('Immutable', () => {