Clarify test-sources docs

Author: mhsmith

README.md

@@ -151,7 +151,7 @@ The following diagram summarises the steps that cibuildwheel takes on each platf
 |  | [`pyodide-version`](https://cibuildwheel.pypa.io/en/stable/options/#pyodide-version) | Specify the Pyodide version to use for `pyodide` platform builds |
 | **Testing** | [`test-command`](https://cibuildwheel.pypa.io/en/stable/options/#test-command) | The command to test each built wheel |
 |  | [`before-test`](https://cibuildwheel.pypa.io/en/stable/options/#before-test) | Execute a shell command before testing each wheel |
-|  | [`test-sources`](https://cibuildwheel.pypa.io/en/stable/options/#test-sources) | Files and folders from the source tree that are copied into an isolated tree before running the tests |
+|  | [`test-sources`](https://cibuildwheel.pypa.io/en/stable/options/#test-sources) | Paths that are copied into the working directory of the tests |
 |  | [`test-requires`](https://cibuildwheel.pypa.io/en/stable/options/#test-requires) | Install Python dependencies before running the tests |
 |  | [`test-extras`](https://cibuildwheel.pypa.io/en/stable/options/#test-extras) | Install your wheel for testing using `extras_require` |
 |  | [`test-groups`](https://cibuildwheel.pypa.io/en/stable/options/#test-groups) | Specify test dependencies from your project's `dependency-groups` |
@@ -162,7 +162,7 @@ The following diagram summarises the steps that cibuildwheel takes on each platf
 |  | [`build-verbosity`](https://cibuildwheel.pypa.io/en/stable/options/#build-verbosity) | Increase/decrease the output of the build |
 
 
-<!--[[[end]]] (sum: TWqEGGMOnt) -->
+<!--[[[end]]] (sum: FxE3nIgFiY) -->
 
 These options can be specified in a pyproject.toml file, or as environment variables, see [configuration docs](https://cibuildwheel.pypa.io/en/latest/configuration/).
 
@@ -245,10 +245,10 @@ See @henryiii's [release post](https://iscinumpy.dev/post/cibuildwheel-3-0-0/) f
 - ✨ Adds CPython 3.14 support, under the [`enable` option](https://cibuildwheel.pypa.io/en/stable/options/#enable) `cpython-prerelease`. This version of cibuildwheel uses 3.14.0b2. (#2390)
 
     _While CPython is in beta, the ABI can change, so your wheels might not be compatible with the final release. For this reason, we don't recommend distributing wheels until RC1, at which point 3.14 will be available in cibuildwheel without the flag._ (#2390)
-- ✨ Adds the [test-sources option](https://cibuildwheel.pypa.io/en/stable/options/#test-sources), and changes the working directory for tests. (#2062, #2284, #2437)
 
-    - If this option is set, cibuildwheel will copy the files and folders specified in `test-sources` into the temporary directory we run from. This is required for iOS builds, but also useful for other platforms, as it allows you to avoid placeholders.
-    - If this option is not set, behaviour matches v2.x - cibuildwheel will run the tests from a temporary directory, and you can use the `{project}` placeholder in the `test-command` to refer to the project directory. (#2420)
+- ✨ Adds the [test-sources option](https://cibuildwheel.pypa.io/en/stable/options/#test-sources), which copies files and folders into the temporary working directory we run tests from. (#2062, #2284, #2420, #2437)
+
+    This is particularly important for iOS builds, which do not support placeholders in the `test-command`, but can also be useful for other platforms.
 
 - ✨ Adds [`dependency-versions`](https://cibuildwheel.pypa.io/en/stable/options/#dependency-versions) inline syntax (#2122)
 - ✨ Improves support for Pyodide builds and adds the experimental [`pyodide-version`](https://cibuildwheel.pypa.io/en/stable/options/#pyodide-version) option, which allows you to specify the version of Pyodide to use for builds. (#2002)
@@ -292,7 +292,7 @@ _15 March 2025_
 - ⚠️ Added warnings when the shorthand values `manylinux1`, `manylinux2010`, `manylinux_2_24`, and `musllinux_1_1` are used to specify the images in linux builds. The shorthand to these (unmaintainted) images will be removed in v3.0. If you want to keep using these images, explicitly opt-in using the full image URL, which can be found in [this file](https://github.com/pypa/cibuildwheel/blob/v2.23.1/cibuildwheel/resources/pinned_docker_images.cfg). (#2312)
 - 🛠 Dependency updates, including a manylinux update which fixes an [issue with rustup](https://github.com/pypa/cibuildwheel/issues/2303). (#2315)
 
-<!-- [[[end]]] (sum: QKx9Hx5znR) -->
+<!-- [[[end]]] (sum: fBN/s9Yq6D) -->
 
 ---
 

docs/changelog.md

@@ -22,10 +22,10 @@ See @henryiii's [release post](https://iscinumpy.dev/post/cibuildwheel-3-0-0/) f
 - ✨ Adds CPython 3.14 support, under the [`enable` option](https://cibuildwheel.pypa.io/en/stable/options/#enable) `cpython-prerelease`. This version of cibuildwheel uses 3.14.0b2. (#2390)
 
     _While CPython is in beta, the ABI can change, so your wheels might not be compatible with the final release. For this reason, we don't recommend distributing wheels until RC1, at which point 3.14 will be available in cibuildwheel without the flag._ (#2390)
-- ✨ Adds the [test-sources option](https://cibuildwheel.pypa.io/en/stable/options/#test-sources), and changes the working directory for tests. (#2062, #2284, #2437)
 
-    - If this option is set, cibuildwheel will copy the files and folders specified in `test-sources` into the temporary directory we run from. This is required for iOS builds, but also useful for other platforms, as it allows you to avoid placeholders.
-    - If this option is not set, behaviour matches v2.x - cibuildwheel will run the tests from a temporary directory, and you can use the `{project}` placeholder in the `test-command` to refer to the project directory. (#2420)
+- ✨ Adds the [test-sources option](https://cibuildwheel.pypa.io/en/stable/options/#test-sources), which copies files and folders into the temporary working directory we run tests from. (#2062, #2284, #2420, #2437)
+
+    This is particularly important for iOS builds, which do not support placeholders in the `test-command`, but can also be useful for other platforms.
 
 - ✨ Adds [`dependency-versions`](https://cibuildwheel.pypa.io/en/stable/options/#dependency-versions) inline syntax (#2122)
 - ✨ Improves support for Pyodide builds and adds the experimental [`pyodide-version`](https://cibuildwheel.pypa.io/en/stable/options/#pyodide-version) option, which allows you to specify the version of Pyodide to use for builds. (#2002)

docs/options.md

@@ -1318,8 +1318,8 @@ Shell command to run tests after the build. The wheel will be installed
 automatically and available for import from the tests. If this variable is not
 set, your wheel will not be installed after building.
 
-To ensure the wheel is imported by your tests (instead of your source copy),
-**Tests are executed from a temporary directory**, outside of your source
+To ensure your tests import the wheel (instead of your source tree),
+**tests are executed from a temporary working directory**, outside of your source
 tree. To access your test code, you have a couple of options:
 
 - You can use the [`test-sources`](#test-sources) setting to copy specific
@@ -1462,12 +1462,12 @@ Platform-specific environment variables are also available:<br/>
 
 
 ### `test-sources` {: #test-sources env-var toml}
-> Files and folders from the source tree that are copied into an isolated tree before running the tests
+> Paths that are copied into the working directory of the tests
 
 A space-separated list of files and folders, relative to the root of the
 project, required for running the tests. If specified, these files and folders
-will be copied into a temporary folder, and that temporary folder will be used
-as the working directory for running the test suite.
+will be copied into the temporary folder which is used as the working directory
+for running the test suite. For more details, see [`test-command`](#test-command).
 
 Platform-specific environment variables are also available:<br/>
 `CIBW_TEST_SOURCES_MACOS` | `CIBW_TEST_SOURCES_WINDOWS` | `CIBW_TEST_SOURCES_LINUX` | `CIBW_TEST_SOURCES_ANDROID` | `CIBW_TEST_SOURCES_IOS` | `CIBW_TEST_SOURCES_PYODIDE`