From d134a05f89c199321fe3166a175a5b8f13179dff Mon Sep 17 00:00:00 2001
From: Simen Bekkhus <sbekkhus91@gmail.com>
Date: Wed, 12 Aug 2020 17:34:59 +0200
Subject: [PATCH 1/2] fix(pretty-format): handle `tagName` not being a string

---
 CHANGELOG.md                                   |  2 ++
 .../src/__tests__/DOMElement.test.ts           | 18 ++++++++++++++++++
 .../pretty-format/src/plugins/DOMElement.ts    |  6 ++++--
 3 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 093d3cc6a965..4c68cb64bea0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,8 @@
 
 ### Fixes
 
+- `[pretty-format]` Handle `tagName` not being a string
+
 ### Chore & Maintenance
 
 ### Performance
diff --git a/packages/pretty-format/src/__tests__/DOMElement.test.ts b/packages/pretty-format/src/__tests__/DOMElement.test.ts
index 6fb25f764095..6ad40955532e 100644
--- a/packages/pretty-format/src/__tests__/DOMElement.test.ts
+++ b/packages/pretty-format/src/__tests__/DOMElement.test.ts
@@ -564,4 +564,22 @@ Testing.`;
       {maxDepth: 2},
     );
   });
+
+  it('handles `tagName` not being a string', () => {
+    expect({
+      name: 'value',
+      tagName: {text: 'param'},
+      type: 'string',
+    }).toPrettyPrintTo(
+      [
+        'Object {',
+        '  "name": "value",',
+        '  "tagName": Object {',
+        '    "text": "param",',
+        '  },',
+        '  "type": "string",',
+        '}',
+      ].join('\n'),
+    );
+  });
 });
diff --git a/packages/pretty-format/src/plugins/DOMElement.ts b/packages/pretty-format/src/plugins/DOMElement.ts
index 75c47737af21..cb855856883e 100644
--- a/packages/pretty-format/src/plugins/DOMElement.ts
+++ b/packages/pretty-format/src/plugins/DOMElement.ts
@@ -25,8 +25,10 @@ const ELEMENT_REGEXP = /^((HTML|SVG)\w*)?Element$/;
 
 const testNode = (val: any) => {
   const constructorName = val.constructor.name;
-  const {nodeType, tagName = ''} = val;
-  const isCustomElement = tagName.includes('-') || val.hasAttribute?.('is');
+  const {nodeType, tagName} = val;
+  const isCustomElement =
+    (typeof tagName === 'string' && tagName.includes('-')) ||
+    val.hasAttribute?.('is');
 
   return (
     (nodeType === ELEMENT_NODE &&

From 4322ed7a347c1092e8386e2cfd5c9d0483505cc8 Mon Sep 17 00:00:00 2001
From: Simen Bekkhus <sbekkhus91@gmail.com>
Date: Wed, 12 Aug 2020 17:37:53 +0200
Subject: [PATCH 2/2] link to PR

---
 CHANGELOG.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4c68cb64bea0..f589a87d9217 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,7 +4,7 @@
 
 ### Fixes
 
-- `[pretty-format]` Handle `tagName` not being a string
+- `[pretty-format]` Handle `tagName` not being a string ([#10397](https://github.com/facebook/jest/pull/10397))
 
 ### Chore & Maintenance