v3.0.0

Highlights

• 01

  Silent divergences, found and closed

  A dotted $set through an array destroyed data. {$set:{"a.0.b":1}} on {a:[5]} silently replaced the element where the server refuses with PathNotViable, and the aggregation twin collapsed an array of subdocuments into one document. $all with $elemMatch members matched nothing. $project dropped computed dotted fields when the parent was absent. distinct returned three values where the server returns one. Every one of these answered differently from MongoDB rather than failing loudly. That is the worst failure mode a test double has, and the one this release set out to eliminate. Every claim was checked against a live mongo:8.0 before any code changed. Four review findings turned out to be wrong: regex i really does fold Unicode case, a matched replaceOne always reports modifiedCount 1, $push modifiers without $each are stored literally, and the server kills a transaction at the failing write. Each is now pinned by a scenario, so the true behaviour cannot be "fixed" into a regression later.

  Read the guide →
• 02

  One ordering rule instead of four

  Cross-type numeric comparison had drifted into four private copies, two of them lossy: the value engine rounded doubles to their shortest decimal rendering, so Decimal128("0.1") compared equal to double 0.1 where the server orders them apart. The update engine kept its own copy plus UTF-16 string ordering, which meant find({v: NumberDecimal("0.1")}) and $pull:{v: NumberDecimal("0.1")} gave opposite answers for the same stored value. Sort, _id equality, $min/$max, $pull, $addToSet and array filters now share one exact rule, and query-style comparisons are type-bracketed as the server's are.

  Read the guide →
• 03

  Your catch block sees the server's exception

  insertMany raised MongoWriteException where the driver raises MongoBulkWriteException: the code and category were the same, but catchability differed, and the mismatch was invisible to a differential lane that only compared error codes. The lane now compares the exception class too, which immediately surfaced ten more scenarios: query errors that should be MongoQueryException, an index build that leaked the storage engine's own exception, malformed update operands arriving as IllegalArgumentException instead of a translated write error.

  Read the guide →
• 04

  Two configurations now refused instead of silently corrupting

  A class-level @Execution(CONCURRENT) ran a class's methods concurrently against one shared context while each method's cleanup dropped the others' databases. A Spring context defining reactive Mongo beans connected to the real server, because the emulator rewires only the synchronous ones. Both now fail fast with an actionable message. Both are breaking for suites that are green today. See the migration notes in the changelog.

  Read the guide →