FEATURE: Make migrations tolerant towards undefined subjects

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', () => {

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', () => {

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', () => {

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', () => {

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', () => {

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;
     }
 );

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', () => {

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', () => {

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', () => {

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', () => {

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 => {

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', () => {