fix: try/catch dockerfile replace (#1022)

lib/workers/branch/dockerfile.js

@@ -9,6 +9,7 @@ function setNewValue(
   newVersion,
   logger
 ) {
+  try {
     logger.debug(`setNewValue: ${depName} = ${newVersion}`);
     const regexReplace = new RegExp(`(^|\n)FROM ${currentVersion}\n`);
     const newFileContent = currentFileContent.replace(
@@ -16,4 +17,8 @@ function setNewValue(
       `$1FROM ${newVersion}\n`
     );
     return newFileContent;
+  } catch (err) {
+    logger.info({ err }, 'Error setting new Dockerfile value');
+    return null;
+  }
 }

test/workers/branch/dockerfile.spec.js

@@ -18,5 +18,19 @@ describe('workers/branch/dockerfile', () => {
       );
       expect(res).toMatchSnapshot();
     });
+    it('returns null on error', () => {
+      const currentFileContent = null;
+      const depName = 'node';
+      const currentVersion = 'node:8';
+      const newVersion = 'node:8@sha256:abcdefghijklmnop';
+      const res = dockerfile.setNewValue(
+        currentFileContent,
+        depName,
+        currentVersion,
+        newVersion,
+        logger
+      );
+      expect(res).toBe(null);
+    });
   });
 });