Improve bad docs around BuildConfiguration.api.

Bug: None
Test: None
Change-Id: I7f6492c9c45f9915855704560dd3919db0146185
(cherry picked from commit 8815b43557969ff52256712a0873f105d6da13a9)
Merged-In: I7f6492c9c45f9915855704560dd3919db0146185

2 files changed, 10 insertions, 1 deletions

diff --git a/ndk/test/builder.py b/ndk/test/builder.py
index 44d3b1555..765afa740 100644
--- a/ndk/test/builder.py
+++ b/ndk/test/builder.py
@@ -165,7 +165,9 @@ class TestBuilder:
         libcxx_scanner = ndk.test.buildtest.scanner.LibcxxTestScanner(
             self.test_options.ndk_path
         )
-        build_api_level = None  # Always use the default.
+        # This is always None for the global config while building. See the comment in
+        # the definition of BuildConfiguration.
+        build_api_level = None
         for abi in self.test_spec.abis:
             for toolchain_file in ndk.test.spec.CMakeToolchainFile:
                 config = ndk.test.spec.BuildConfiguration(
diff --git a/ndk/test/spec.py b/ndk/test/spec.py
index c7ade3e88..33a3494c6 100644
--- a/ndk/test/spec.py
+++ b/ndk/test/spec.py
@@ -100,6 +100,13 @@ class BuildConfiguration:
     """
 
     abi: Abi
+    # This is always None for the global config while building. Each test will fill in
+    # the appropriate value for the test (based on `APP_PLATFORM` or similar). It is
+    # still a part of the BuildConfiguration class because we do not have separate
+    # classes for build config *input* (the BuildConfiguration created by
+    # TestBuilder.find_tests) and build config *output* (the result decided and
+    # serialized by the test, which needs to be read when the test is later run by
+    # run_tests.py).
     api: Optional[int]
     toolchain_file: CMakeToolchainFile