Emit correct metadata from StreamLogHandler

[slashmo]

Return the correct metadata to log from the StreamLogHandler.

Motivation:

At the moment, StreamLogHandler always returns the explicitly passed metadata as the metadata to log. This throws away any metadata provided by the registered MetadataProvider.

Modifications:

Return the merged metadata, both explicit and provided.

Result:

When using the StreamLogHandler, metadata set through MetadataProviders will now correctly show up in the logs.

[ktoso]

Ouch, nice catch -- thanks @slashmo.

We should have a test that covers this, can you please add the following test case in LoggingTests around the StreamLogHandler tests:

    func testStreamLogHandlerWritesIncludeMetadataProviderMetadata() {
        let interceptStream = InterceptStream()
        LoggingSystem.bootstrapInternal({ _, metadataProvider in
            StreamLogHandler(label: "test", stream: interceptStream, metadataProvider: metadataProvider)
        }, metadataProvider: .exampleMetadataProvider)
        let log = Logger(label: "test")

        let testString = "my message is better than yours"
        log.critical("\(testString)")

        let messageSucceeded = interceptStream.interceptedText?.trimmingCharacters(in: .whitespacesAndNewlines).hasSuffix(testString)

        XCTAssertTrue(messageSucceeded ?? false)
        XCTAssertEqual(interceptStream.strings.count, 1)
        let message = interceptStream.strings.first!
        XCTAssertTrue(message.contains("example=example-value"), "message must contain metadata, was: \(message)")
    }

Thank you!

[slashmo]

can you please add the following test case in LoggingTests
@ktoso

Good point, I'll add it.

[ktoso]

LGTM, thanks for adding the test and spotting the issue