Fix ckb export EEXIST failures by using per-range subdirectories

[Copilot]

ckb export refuses to write into a non-empty directory (EEXIST, errno 17). All export tests shared a single export/ directory, causing cascading failures across 8 of 11 tests once the first export populated it.

Changes

• Per-range subdirectory: _export_blocks(from, to) now targets export/{from}-{to}/ instead of the shared export/ dir — each call gets a clean directory
• Filename normalization fallback: after export, if ckb-{from}-{to}.jsonl isn't found, glob-discovers the single .jsonl in the range dir and renames it to the expected name — handles any ckb export naming variations
• Explicit error handling: raises FileNotFoundError or RuntimeError when the export produces zero or multiple .jsonl files, instead of silently returning a nonexistent path
• Housekeeping: removed unused time import; fixed implicit f-string concatenation in test_10

# Before — all ranges share one dir, second export hits EEXIST
run_command(f"./ckb export --target {self.export_dir} --from {from_block} --to {to_block}")

# After — each range gets its own clean subdirectory
range_dir = os.path.join(self.export_dir, f"{from_block}-{to_block}")
run_command(f"mkdir -p {range_dir}")
run_command(f"./ckb export --target {range_dir} --from {from_block} --to {to_block}")

Original prompt

Problem

The CI integration tests in test_cases/ckb_command/test_export_import.py are failing with 8 out of 11 tests broken. The failing job logs: https://github.com/cryptape/ckb-py-integration-test/actions/runs/22847094649

Root Cause

The ckb export command refuses to export when the target directory already contains files, throwing:

Export error: Os { code: 17, kind: AlreadyExists, message: "File exists" }

The _export_blocks() helper method exports all ranges to the same shared export/ directory. When test_01 exports blocks 1-50, it creates a file in export/. When test_02 tries to export blocks 1-10 to the same directory, ckb export sees the existing file and fails with EEXIST. This cascades to all subsequent tests.

Two failure modes observed

1. Export tests (test_01, test_02, test_03): The export command fails or the expected output filename ckb-{from}-{to}.jsonl doesn't match what ckb export actually generates, resulting in FileNotFoundError / AssertionError: File not found.

2. Import tests (test_05, test_07, test_08, test_09, test_10): These call _export_blocks(1, 50) again. Since the expected file doesn't exist (wrong name or previous failure), the cache check (if os.path.exists(expected)) fails, and it tries to re-export into the already-populated directory, triggering EEXIST.

Required Fix

Modify the _export_blocks() method in test_cases/ckb_command/test_export_import.py to use a separate subdirectory per block range for each export operation. This avoids the EEXIST conflict because each ckb export call gets its own clean target directory.

Current code (lines 60-69):

def _export_blocks(self, from_block, to_block):
    """Export a range from the source node, return the output file path."""
    expected = os.path.join(self.export_dir, f"ckb-{from_block}-{to_block}.jsonl")
    if os.path.exists(expected):
        return expected
    run_command(
        f"cd {self.node.ckb_dir} && ./ckb export "
        f"--target {self.export_dir} --from {from_block} --to {to_block}"
    )
    return expected

Should be changed to use a per-range subdirectory:

def _export_blocks(self, from_block, to_block):
    """Export a range from the source node, return the output file path."""
    range_dir = os.path.join(self.export_dir, f"{from_block}-{to_block}")
    expected = os.path.join(range_dir, f"ckb-{from_block}-{to_block}.jsonl")
    if os.path.exists(expected):
        return expected
    # Use a dedicated subdirectory per range to avoid EEXIST from ckb export
    run_command(f"mkdir -p {range_dir}")
    run_command(
        f"cd {self.node.ckb_dir} && ./ckb export "
        f"--target {range_dir} --from {from_block} --to {to_block}"
    )
    return expected

Additionally, if ckb export generates a file with a different naming convention than ckb-{from}-{to}.jsonl, the method should discover the actual output file. Add a fallback using glob to find the exported .jsonl file in the range directory and rename/return it:

import glob

def _export_blocks(self, from_block, to_block):
    """Export a range from the source node, return the output file path."""
    range_dir = os.path.join(self.export_dir, f"{from_block}-{to_block}")
    expected = os.path.join(range_dir, f"ckb-{from_block}-{to_block}.jsonl")
    if os.path.exists(expected):
        return expected
    run_command(f"mkdir -p {range_dir}")
    run_command(
        f"cd {self.node.ckb_dir} && ./ckb export "
        f"--target {range_dir} --from {from_block} --to {to_block}"
    )
    # If expected file not found, locate the actual exported file and rename it
    if not os.path.exists(expected):
        files = glob.glob(os.path.join(range_dir, "*.jsonl"))
        if len(files) == 1:
            os.rename(files[0], expected)
    return expected

Only the file test_cases/ckb_command/test_export_import.py needs to be changed. The _export_blocks method is the only place that needs modification.

The following is the prior conversation context from the user's chat exploration (may be truncated):

User: 帮我分析一下这个报错，解决一下这个问题

Assistant: ## 分析报告

问题根因

这次 CI 失败的 核心原因 是：ckb export 命令在导出时，目标目录（export/）中已经存在同名文件，导致报错：

Export error: Os { code: 17, kind: AlreadyExists, message: "File exists" }

这个错误是 Linux 系统错误码 EEXIST (17)，意味着 ckb export 不支持覆盖已有文件，而测试代码中多个测试方法尝试导出相同 block 范围到同一个目录。

---

失败分为两类

第 1 类：前 3 个 export 测试（test_01、test_02、test_03）

这些测试调用 _export_blocks() 进行导出，但导出命令本身静默失败了（exit code 非 0 抛出异常被忽略了，或者第一次就已经失败）。导出文件没有被成功创建，后续断言找不到文件：

FAILED test_01 - AssertionError: File not found: .../export/ckb-1-50.jsonl
FAILED test_02 - FileNotFoundError: .../export/ckb-1-10.jsonl
FAILED test_03 - FileNotFoundError: .../export/ckb-10-20.jsonl

关键线索：_export_blocks() 方法里有一个短路逻辑：

</details>



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