{* ../../docs_src/settings/app02_an_py310/test_main.py hl[9:10,13,21] *}

在依赖项覆盖中，我们在创建新的 `Settings` 对象时为 `admin_email` 设置了一个新值，然后返回该新对象。

然后我们可以测试它是否被使用。

## 读取 `.env` 文件 { #reading-a-env-file }

如果你有许多设置可能经常变化，或在不同环境中不同，那么把它们放进一个文件中，然后像环境变量一样从中读取，可能非常有用。

这种做法非常常见：这些环境变量通常放在名为 `.env` 的文件中，该文件被称为 “dotenv”。

/// tip | 提示

以点（`.`）开头的文件在类 Unix 系统（如 Linux 和 macOS）中是隐藏文件。

		}
	}

	contentBytes, err := io.ReadAll(resp.Body)
	if err != nil {
		return content, AdminError{
			Code:       AdminUpdateUnexpectedFailure,
			Message:    fmt.Sprintf("Error reading response. %s", err),
			StatusCode: http.StatusInternalServerError,
		}
	}

	return string(contentBytes), nil
}

func releaseInfoToReleaseTime(releaseInfo string) (releaseTime time.Time, err error) {

// license that can be found in the LICENSE file.

package bufio

import (
	"bytes"
	"errors"
	"io"
	"unicode/utf8"
)

// Scanner provides a convenient interface for reading data such as
// a file of newline-delimited lines of text. Successive calls to
// the [Scanner.Scan] method will step through the 'tokens' of a file, skipping
// the bytes between the tokens. The specification of a token is

     * even entire message) that simultaneously:
     *
     * - _shouldn't_ be null, so we don't annotate it with @Nullable
     *
     * - _can_ be null without causing a runtime failure (because we don't want the interesting
     *   details of precondition failure to be hidden by an exception we throw about an unexpectedly
     *   null _failure message_)
     *

     * even entire message) that simultaneously:
     *
     * - _shouldn't_ be null, so we don't annotate it with @Nullable
     *
     * - _can_ be null without causing a runtime failure (because we don't want the interesting
     *   details of precondition failure to be hidden by an exception we throw about an unexpectedly
     *   null _failure message_)
     *

«Контекстные менеджеры» — это любые объекты Python, которые можно использовать в операторе `with`.

Например, [можно использовать `with` для чтения файла](https://docs.python.org/3/tutorial/inputoutput.html#reading-and-writing-files):

```Python
with open("./somefile.txt") as f:
    contents = f.read()
    print(contents)
```

   * body. This was misleading for tracing because it was too early.
   */
  open fun responseBodyStart(call: Call) {
  }

  /**
   * Invoked immediately after receiving a response body and completing reading it.
   *
   * Will only be invoked for requests having a response body e.g. won't be invoked for a web socket
   * upgrade.
   *

    // in a recursive loop.  Sneaky.
    if (level == stimuli.length) {
      // We've filled the array.
      compareResultsForThisListOfStimuli();
    } else {
      // Keep recursing to fill the array.
      for (Stimulus<E, ? super I> stimulus : getStimulusValues()) {
        stimuli[level] = stimulus;
        recurse(level + 1);
      }
    }
  }

        try {
            context.extensions = readCoreExtensionsDescriptor(context);
        } catch (Exception e) {
            context.parsingFailed = true;
            parserRequest.logger().error("Error reading core extensions descriptor", e);
        }

        // CI detection
        context.ciInfo = detectCI(context);

        // only if not failed so far; otherwise we may have no options to validate

 *  Fix: Don't leak file handles when a cache disk write fails.

 *  Fix: Don't hang when the public suffix database cannot be loaded. We had a bug where a failure
    reading the public suffix database would cause subsequent reads to hang when they should have
    crashed.

 *  Fix: Avoid `InetAddress.getCanonicalHostName()` in MockWebServer. This avoids problems if the