diff --git a/src/tests/frontend/specs/easysync-assembler.js b/src/tests/frontend/specs/easysync-assembler.js
index d9ce04ae..070e1bd8 100644
--- a/src/tests/frontend/specs/easysync-assembler.js
+++ b/src/tests/frontend/specs/easysync-assembler.js
@@ -1,6 +1,7 @@
 'use strict';
 
 const Changeset = require('../../../static/js/Changeset');
+const {poolOrArray} = require('../easysync-helper.js');
 
 describe('easysync-assembler', function () {
   it('opAssembler', async function () {
@@ -18,6 +19,137 @@ describe('easysync-assembler', function () {
     expect(assem.toString()).to.equal(x);
   });
 
+  it('smartOpAssembler ignore additional pure keeps (no attributes)', async function () {
+    const x = '-c*3*4+6|1+1=5';
+    const iter = Changeset.opIterator(x);
+    const assem = Changeset.smartOpAssembler();
+    while (iter.hasNext()) assem.append(iter.next());
+    assem.endDocument();
+    expect(assem.toString()).to.equal('-c*3*4+6|1+1');
+  });
+
+  it('smartOpAssembler merge consecutive + ops without multiline', async function () {
+    const x = '-c*3*4+6*3*4+1*3*4+9=5';
+    const iter = Changeset.opIterator(x);
+    const assem = Changeset.smartOpAssembler();
+    while (iter.hasNext()) assem.append(iter.next());
+    assem.endDocument();
+    expect(assem.toString()).to.equal('-c*3*4+g');
+  });
+
+  it('smartOpAssembler merge consecutive + ops with multiline', async function () {
+    const x = '-c*3*4+6*3*4|1+1*3*4|9+f*3*4+k=5';
+    const iter = Changeset.opIterator(x);
+    const assem = Changeset.smartOpAssembler();
+    while (iter.hasNext()) assem.append(iter.next());
+    assem.endDocument();
+    expect(assem.toString()).to.equal('-c*3*4|a+m*3*4+k');
+  });
+
+  it('smartOpAssembler merge consecutive - ops without multiline', async function () {
+    const x = '-c-6-1-9=5';
+    const iter = Changeset.opIterator(x);
+    const assem = Changeset.smartOpAssembler();
+    while (iter.hasNext()) assem.append(iter.next());
+    assem.endDocument();
+    expect(assem.toString()).to.equal('-s');
+  });
+
+  it('smartOpAssembler merge consecutive - ops with multiline', async function () {
+    const x = '-c-6|1-1|9-f-k=5';
+    const iter = Changeset.opIterator(x);
+    const assem = Changeset.smartOpAssembler();
+    while (iter.hasNext()) assem.append(iter.next());
+    assem.endDocument();
+    expect(assem.toString()).to.equal('|a-y-k');
+  });
+
+  it('smartOpAssembler merge consecutive = ops without multiline', async function () {
+    const x = '-c*3*4=6*2*4=1*3*4=f*3*4=2*3*4=a=k=5';
+    const iter = Changeset.opIterator(x);
+    const assem = Changeset.smartOpAssembler();
+    while (iter.hasNext()) assem.append(iter.next());
+    assem.endDocument();
+    expect(assem.toString()).to.equal('-c*3*4=6*2*4=1*3*4=r');
+  });
+
+  it('smartOpAssembler merge consecutive = ops with multiline', async function () {
+    const x = '-c*3*4=6*2*4|1=1*3*4|9=f*3*4|2=2*3*4=a*3*4=1=k=5';
+    const iter = Changeset.opIterator(x);
+    const assem = Changeset.smartOpAssembler();
+    while (iter.hasNext()) assem.append(iter.next());
+    assem.endDocument();
+    expect(assem.toString()).to.equal('-c*3*4=6*2*4|1=1*3*4|b=h*3*4=b');
+  });
+
+  it('smartOpAssembler ignore + ops with ops.chars === 0', async function () {
+    const x = '-c*3*4+6*3*4+0*3*4+1+0*3*4+1';
+    const iter = Changeset.opIterator(x);
+    const assem = Changeset.smartOpAssembler();
+    while (iter.hasNext()) assem.append(iter.next());
+    assem.endDocument();
+    expect(assem.toString()).to.equal('-c*3*4+8');
+  });
+
+  it('smartOpAssembler ignore - ops with ops.chars === 0', async function () {
+    const x = '-c-6-0-1-0-1';
+    const iter = Changeset.opIterator(x);
+    const assem = Changeset.smartOpAssembler();
+    while (iter.hasNext()) assem.append(iter.next());
+    assem.endDocument();
+    expect(assem.toString()).to.equal('-k');
+  });
+
+  it('smartOpAssembler append + op with text', async function () {
+    const assem = Changeset.smartOpAssembler();
+    const pool = poolOrArray([
+      'attr1,1',
+      'attr2,2',
+      'attr3,3',
+      'attr4,4',
+      'attr5,5',
+    ]);
+
+    assem.appendOpWithText('+', 'test', '*3*4*5', pool);
+    assem.appendOpWithText('+', 'test', '*3*4*5', pool);
+    assem.appendOpWithText('+', 'test', '*1*4*5', pool);
+    assem.endDocument();
+    expect(assem.toString()).to.equal('*3*4*5+8*1*4*5+4');
+  });
+
+  it('smartOpAssembler append + op with multiline text', async function () {
+    const assem = Changeset.smartOpAssembler();
+    const pool = poolOrArray([
+      'attr1,1',
+      'attr2,2',
+      'attr3,3',
+      'attr4,4',
+      'attr5,5',
+    ]);
+
+    assem.appendOpWithText('+', 'test\ntest', '*3*4*5', pool);
+    assem.appendOpWithText('+', '\ntest\n', '*3*4*5', pool);
+    assem.appendOpWithText('+', '\ntest', '*1*4*5', pool);
+    assem.endDocument();
+    expect(assem.toString()).to.equal('*3*4*5|3+f*1*4*5|1+1*1*4*5+4');
+  });
+
+  it('smartOpAssembler clear should empty internal assemblers', async function () {
+    const x = '-c*3*4+6|3=az*asdf0*1*2*3+1=1-1+1*0+1=1-1+1|c=c-1';
+    const iter = Changeset.opIterator(x);
+    const assem = Changeset.smartOpAssembler();
+    assem.append(iter.next());
+    assem.append(iter.next());
+    assem.append(iter.next());
+    assem.clear();
+    assem.append(iter.next());
+    assem.append(iter.next());
+    assem.clear();
+    while (iter.hasNext()) assem.append(iter.next());
+    assem.endDocument();
+    expect(assem.toString()).to.equal('-1+1*0+1=1-1+1|c=c-1');
+  });
+
   describe('append atext to assembler', function () {
     const testAppendATextToAssembler = (testId, atext, correctOps) => {
       it(`testAppendATextToAssembler#${testId}`, async function () {