diff --git a/src/core/client/stream/test/__snapshots__/postComment.spec.tsx.snap b/src/core/client/stream/test/__snapshots__/postComment.spec.tsx.snap
index 145f4be33..69d6009dd 100644
--- a/src/core/client/stream/test/__snapshots__/postComment.spec.tsx.snap
+++ b/src/core/client/stream/test/__snapshots__/postComment.spec.tsx.snap
@@ -49,6 +49,296 @@ exports[`post a comment 1`] = `
           </div>
         </div>
       </div>
+      <form
+        autoComplete="off"
+        className="PostCommentForm-root"
+        id="comments-postCommentForm-form"
+        onSubmit={[Function]}
+      >
+        <div
+          className="HorizontalGutter-root HorizontalGutter-full"
+        >
+          <div>
+            <label
+              className="AriaInfo-root"
+              htmlFor="comments-postCommentForm-field"
+            >
+              Post a comment
+            </label>
+            <div>
+              <div
+                className=""
+              >
+                <div
+                  className="Toolbar-toolbar"
+                >
+                  <button
+                    className="Button-button"
+                    disabled={false}
+                    onClick={[Function]}
+                    title="Bold"
+                    type="button"
+                  >
+                    <span
+                      aria-hidden="true"
+                      className="Icon-root Icon-sm"
+                    >
+                      format_bold
+                    </span>
+                  </button>
+                  <button
+                    className="Button-button"
+                    disabled={false}
+                    onClick={[Function]}
+                    title="Italic"
+                    type="button"
+                  >
+                    <span
+                      aria-hidden="true"
+                      className="Icon-root Icon-sm"
+                    >
+                      format_italic
+                    </span>
+                  </button>
+                  <button
+                    className="Button-button"
+                    disabled={false}
+                    onClick={[Function]}
+                    title="Blockquote"
+                    type="button"
+                  >
+                    <span
+                      aria-hidden="true"
+                      className="Icon-root Icon-sm"
+                    >
+                      format_quote
+                    </span>
+                  </button>
+                </div>
+                <div
+                  aria-placeholder="Post a comment"
+                  className="RTE-contentEditable RTE-content"
+                  contentEditable={true}
+                  dangerouslySetInnerHTML={
+                    Object {
+                      "__html": "<strong>Hello world!</strong>",
+                    }
+                  }
+                  id="comments-postCommentForm-field"
+                  onBlur={[Function]}
+                  onChange={[Function]}
+                  onCut={[Function]}
+                  onFocus={[Function]}
+                  onInput={[Function]}
+                  onKeyDown={[Function]}
+                  onPaste={[Function]}
+                  onSelect={[Function]}
+                />
+              </div>
+            </div>
+          </div>
+          <div
+            className="Flex-root Flex-flex Flex-justifySpaceBetween Flex-alignFlexStart Flex-directionRow"
+          >
+            <div
+              className="PostCommentForm-poweredBy"
+            >
+              <span
+                className="Typography-root Typography-inputDescription Typography-colorTextSecondary"
+              >
+                Powered by 
+                <span
+                  className="Typography-root Typography-heading4 Typography-colorTextPrimary"
+                >
+                  ⁨The Coral Project⁩
+                </span>
+              </span>
+            </div>
+            <button
+              className="BaseButton-root Button-root Button-sizeRegular Button-colorPrimary Button-variantFilled Button-disabled"
+              disabled={true}
+              onBlur={[Function]}
+              onFocus={[Function]}
+              onMouseDown={[Function]}
+              onMouseOut={[Function]}
+              onMouseOver={[Function]}
+              onTouchEnd={[Function]}
+              type="submit"
+            >
+              Submit
+            </button>
+          </div>
+        </div>
+      </form>
+    </div>
+    <div
+      aria-live="polite"
+      className="HorizontalGutter-root HorizontalGutter-full"
+      id="talk-comments-stream-log"
+      role="log"
+    >
+      <div
+        className="HorizontalGutter-root HorizontalGutter-full"
+      >
+        <div
+          className="Comment-root"
+          role="article"
+        >
+          <div
+            className="Flex-root TopBar-root Flex-flex Flex-halfItemGutter Flex-alignBaseline Flex-directionColumn"
+          >
+            <span
+              className="Typography-root Typography-heading3 Typography-colorTextPrimary Username-root"
+            >
+              Markus
+            </span>
+            <time
+              className="Timestamp-root RelativeTime-root"
+              dateTime="2018-08-31T16:14:09.617Z"
+              title="2018-08-31T16:14:09.617Z"
+            >
+              2018-08-31T16:14:09.617Z
+            </time>
+          </div>
+          <div
+            className="HTMLContent-root"
+            dangerouslySetInnerHTML={
+              Object {
+                "__html": "<strong>Hello world!</strong>",
+              }
+            }
+          />
+          <div
+            className="Comment-footer"
+          />
+        </div>
+      </div>
+      <div
+        className="HorizontalGutter-root HorizontalGutter-full"
+      >
+        <div
+          className="Comment-root"
+          role="article"
+        >
+          <div
+            className="Flex-root TopBar-root Flex-flex Flex-halfItemGutter Flex-alignBaseline Flex-directionColumn"
+          >
+            <span
+              className="Typography-root Typography-heading3 Typography-colorTextPrimary Username-root"
+            >
+              Markus
+            </span>
+            <time
+              className="Timestamp-root RelativeTime-root"
+              dateTime="2018-07-06T18:24:00.000Z"
+              title="2018-07-06T18:24:00.000Z"
+            >
+              2018-07-06T18:24:00.000Z
+            </time>
+          </div>
+          <div
+            className="HTMLContent-root"
+            dangerouslySetInnerHTML={
+              Object {
+                "__html": "Joining Too",
+              }
+            }
+          />
+          <div
+            className="Comment-footer"
+          />
+        </div>
+      </div>
+      <div
+        className="HorizontalGutter-root HorizontalGutter-full"
+      >
+        <div
+          className="Comment-root"
+          role="article"
+        >
+          <div
+            className="Flex-root TopBar-root Flex-flex Flex-halfItemGutter Flex-alignBaseline Flex-directionColumn"
+          >
+            <span
+              className="Typography-root Typography-heading3 Typography-colorTextPrimary Username-root"
+            >
+              Lukas
+            </span>
+            <time
+              className="Timestamp-root RelativeTime-root"
+              dateTime="2018-07-06T18:20:00.000Z"
+              title="2018-07-06T18:20:00.000Z"
+            >
+              2018-07-06T18:20:00.000Z
+            </time>
+          </div>
+          <div
+            className="HTMLContent-root"
+            dangerouslySetInnerHTML={
+              Object {
+                "__html": "What's up?",
+              }
+            }
+          />
+          <div
+            className="Comment-footer"
+          />
+        </div>
+      </div>
+    </div>
+  </div>
+</div>
+`;
+
+exports[`post a comment 2`] = `
+<div
+  className="Flex-root App-root Flex-flex Flex-justifyCenter"
+>
+  <div
+    className="HorizontalGutter-root Stream-root HorizontalGutter-double"
+  >
+    <div
+      className="HorizontalGutter-root HorizontalGutter-half"
+    >
+      <div
+        className="Flex-root"
+      >
+        <div
+          className="Flex-flex Flex-halfItemGutter Flex-wrap"
+        >
+          <div
+            className="Typography-root Typography-bodyCopy Typography-colorTextPrimary"
+          >
+            Signed in as 
+            <span
+              className="Typography-root Typography-bodyCopyBold Typography-colorTextPrimary"
+            >
+              Markus
+            </span>
+            .
+          </div>
+          <div
+            className="Flex-root Typography-root Typography-bodyCopy Typography-colorTextPrimary Flex-flex"
+          >
+            <span>
+              Not you? 
+            </span>
+            <button
+              className="BaseButton-root Button-root Button-sizeSmall Button-colorPrimary Button-variantUnderlined"
+              onBlur={[Function]}
+              onClick={[Function]}
+              onFocus={[Function]}
+              onMouseDown={[Function]}
+              onMouseOut={[Function]}
+              onMouseOver={[Function]}
+              onTouchEnd={[Function]}
+              type="button"
+            >
+              Sign Out
+            </button>
+          </div>
+        </div>
+      </div>
       <form
         autoComplete="off"
         className="PostCommentForm-root"
@@ -210,7 +500,7 @@ exports[`post a comment 1`] = `
             className="HTMLContent-root"
             dangerouslySetInnerHTML={
               Object {
-                "__html": "<strong>Hello world</strong>",
+                "__html": "<strong>Hello world! (from server)</strong>",
               }
             }
           />
diff --git a/src/core/client/stream/test/postComment.spec.tsx b/src/core/client/stream/test/postComment.spec.tsx
index 0546901db..670609d89 100644
--- a/src/core/client/stream/test/postComment.spec.tsx
+++ b/src/core/client/stream/test/postComment.spec.tsx
@@ -46,7 +46,7 @@ beforeEach(() => {
                 node: {
                   id: "comment-x",
                   author: users[0],
-                  body: "<strong>Hello world</strong>",
+                  body: "<strong>Hello world! (from server)</strong>",
                   createdAt: "2018-07-06T18:24:00.000Z",
                 },
               },
@@ -97,8 +97,11 @@ it("post a comment", async () => {
   testRenderer.root
     .findByProps({ id: "comments-postCommentForm-form" })
     .props.onSubmit();
+  // Test optimistic response.
+  expect(testRenderer.toJSON()).toMatchSnapshot();
 
   // Wait for loading.
   await timeout();
+  // Test after server response.
   expect(testRenderer.toJSON()).toMatchSnapshot();
 });