diff --git a/src/editor/caret.js b/src/editor/caret.js
index c56022d8c6..9b0fa14cfc 100644
--- a/src/editor/caret.js
+++ b/src/editor/caret.js
@@ -40,7 +40,7 @@ export function setCaretPosition(editor, model, caretPosition) {
     sel.addRange(range);
 }
 
-function getLineAndNodePosition(model, caretPosition) {
+export function getLineAndNodePosition(model, caretPosition) {
     const {parts} = model;
     const partIndex = caretPosition.index;
     const lineResult = findNodeInLineForPart(parts, partIndex);
diff --git a/test/editor/caret-test.js b/test/editor/caret-test.js
new file mode 100644
index 0000000000..9da28bff95
--- /dev/null
+++ b/test/editor/caret-test.js
@@ -0,0 +1,205 @@
+/*
+Copyright 2019 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import expect from 'expect';
+import {getLineAndNodePosition} from "../../src/editor/caret";
+import EditorModel from "../../src/editor/model";
+import {createPartCreator} from "./mock";
+
+describe('editor/caret: DOM position for caret', function() {
+    describe('basic text handling', function() {
+        it('at end of single line', function() {
+            const pc = createPartCreator();
+            const model = new EditorModel([
+                pc.plain("hello"),
+            ]);
+            const {offset, lineIndex, nodeIndex} =
+                getLineAndNodePosition(model, {index: 0, offset: 5});
+            expect(lineIndex).toBe(0);
+            expect(nodeIndex).toBe(0);
+            expect(offset).toBe(5);
+        });
+        it('at start of single line', function() {
+            const pc = createPartCreator();
+            const model = new EditorModel([
+                pc.plain("hello"),
+            ]);
+            const {offset, lineIndex, nodeIndex} =
+                getLineAndNodePosition(model, {index: 0, offset: 0});
+            expect(lineIndex).toBe(0);
+            expect(nodeIndex).toBe(0);
+            expect(offset).toBe(0);
+        });
+        it('at middle of single line', function() {
+            const pc = createPartCreator();
+            const model = new EditorModel([
+                pc.plain("hello"),
+            ]);
+            const {offset, lineIndex, nodeIndex} =
+                getLineAndNodePosition(model, {index: 0, offset: 2});
+            expect(lineIndex).toBe(0);
+            expect(nodeIndex).toBe(0);
+            expect(offset).toBe(2);
+        });
+    });
+    describe('handling line breaks', function() {
+        it('at end of last line', function() {
+            const pc = createPartCreator();
+            const model = new EditorModel([
+                pc.plain("hello"),
+                pc.newline(),
+                pc.plain("world"),
+            ]);
+            const {offset, lineIndex, nodeIndex} =
+                getLineAndNodePosition(model, {index: 2, offset: 5});
+            expect(lineIndex).toBe(1);
+            expect(nodeIndex).toBe(0);
+            expect(offset).toBe(5);
+        });
+        it('at start of last line', function() {
+            const pc = createPartCreator();
+            const model = new EditorModel([
+                pc.plain("hello"),
+                pc.newline(),
+                pc.plain("world"),
+            ]);
+            const {offset, lineIndex, nodeIndex} =
+                getLineAndNodePosition(model, {index: 2, offset: 0});
+            expect(lineIndex).toBe(1);
+            expect(nodeIndex).toBe(0);
+            expect(offset).toBe(0);
+        });
+        it('in empty line', function() {
+            const pc = createPartCreator();
+            const model = new EditorModel([
+                pc.plain("hello"),
+                pc.newline(),
+                pc.newline(),
+                pc.plain("world"),
+            ]);
+            const {offset, lineIndex, nodeIndex} =
+                getLineAndNodePosition(model, {index: 1, offset: 1});
+            expect(lineIndex).toBe(1);
+            expect(nodeIndex).toBe(-1);
+            expect(offset).toBe(0);
+        });
+        it('after empty line', function() {
+            const pc = createPartCreator();
+            const model = new EditorModel([
+                pc.plain("hello"),
+                pc.newline(),
+                pc.newline(),
+                pc.plain("world"),
+            ]);
+            const {offset, lineIndex, nodeIndex} =
+                getLineAndNodePosition(model, {index: 3, offset: 0});
+            expect(lineIndex).toBe(2);
+            expect(nodeIndex).toBe(0);
+            expect(offset).toBe(0);
+        });
+    });
+    describe('handling non-editable parts and caret nodes', function() {
+        it('at start of non-editable part (with plain text around)', function() {
+            const pc = createPartCreator();
+            const model = new EditorModel([
+                pc.plain("hello"),
+                pc.userPill("Alice", "@alice:hs.tld"),
+                pc.plain("!"),
+            ]);
+            const {offset, lineIndex, nodeIndex} =
+                getLineAndNodePosition(model, {index: 1, offset: 0});
+            expect(lineIndex).toBe(0);
+            expect(nodeIndex).toBe(0);
+            expect(offset).toBe(5);
+        });
+        it('in middle of non-editable part (with plain text around)', function() {
+            const pc = createPartCreator();
+            const model = new EditorModel([
+                pc.plain("hello"),
+                pc.userPill("Alice", "@alice:hs.tld"),
+                pc.plain("!"),
+            ]);
+            const {offset, lineIndex, nodeIndex} =
+                getLineAndNodePosition(model, {index: 1, offset: 2});
+            expect(lineIndex).toBe(0);
+            expect(nodeIndex).toBe(2);
+            expect(offset).toBe(0);
+        });
+        it('at start of non-editable part (without plain text around)', function() {
+            const pc = createPartCreator();
+            const model = new EditorModel([
+                pc.userPill("Alice", "@alice:hs.tld"),
+            ]);
+            const {offset, lineIndex, nodeIndex} =
+                getLineAndNodePosition(model, {index: 0, offset: 0});
+            expect(lineIndex).toBe(0);
+            //presumed nodes on line are (caret, pill, caret)
+            expect(nodeIndex).toBe(0);
+            expect(offset).toBe(0);
+        });
+        it('in middle of non-editable part (without plain text around)', function() {
+            const pc = createPartCreator();
+            const model = new EditorModel([
+                pc.userPill("Alice", "@alice:hs.tld"),
+            ]);
+            const {offset, lineIndex, nodeIndex} =
+                getLineAndNodePosition(model, {index: 0, offset: 1});
+            expect(lineIndex).toBe(0);
+            //presumed nodes on line are (caret, pill, caret)
+            expect(nodeIndex).toBe(2);
+            expect(offset).toBe(0);
+        });
+        it('in middle of a first non-editable part, with another one following', function() {
+            const pc = createPartCreator();
+            const model = new EditorModel([
+                pc.userPill("Alice", "@alice:hs.tld"),
+                pc.userPill("Bob", "@bob:hs.tld"),
+            ]);
+            const {offset, lineIndex, nodeIndex} =
+                getLineAndNodePosition(model, {index: 0, offset: 1});
+            expect(lineIndex).toBe(0);
+            //presumed nodes on line are (caret, pill, caret, pill, caret)
+            expect(nodeIndex).toBe(2);
+            expect(offset).toBe(0);
+        });
+        it('in start of a second non-editable part, with another one before it', function() {
+            const pc = createPartCreator();
+            const model = new EditorModel([
+                pc.userPill("Alice", "@alice:hs.tld"),
+                pc.userPill("Bob", "@bob:hs.tld"),
+            ]);
+            const {offset, lineIndex, nodeIndex} =
+                getLineAndNodePosition(model, {index: 1, offset: 0});
+            expect(lineIndex).toBe(0);
+            //presumed nodes on line are (caret, pill, caret, pill, caret)
+            expect(nodeIndex).toBe(2);
+            expect(offset).toBe(0);
+        });
+        it('in middle of a second non-editable part, with another one before it', function() {
+            const pc = createPartCreator();
+            const model = new EditorModel([
+                pc.userPill("Alice", "@alice:hs.tld"),
+                pc.userPill("Bob", "@bob:hs.tld"),
+            ]);
+            const {offset, lineIndex, nodeIndex} =
+                getLineAndNodePosition(model, {index: 1, offset: 1});
+            expect(lineIndex).toBe(0);
+            //presumed nodes on line are (caret, pill, caret, pill, caret)
+            expect(nodeIndex).toBe(4);
+            expect(offset).toBe(0);
+        });
+    });
+});