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Deterministic builds

A deterministic build, e.g. with ContinuousIntegrationBuild=true on a build server, replaces the path of the repository with /_/ in the compiled code, so the path of the test file, e.g. /_/Tests/AlbumTests.cs, no longer leads to its snapshots. The package records the real path of the repository in the test assembly when it is built, so the snapshots are found in such a build as well, without any configuration.

A snapshot is identified by the path of its test file relative to the repository, e.g. Tests/AlbumTests.cs, which is the same on every machine and in every build.

This needs two things, which a usual setup provides:

  • The test project references the aweXpect.Snapshots package, directly or through another project, as the build targets that record the path come with the package.
  • The repository provides source control information, which the .NET SDK does for a git repository.

Without them, a snapshot is identified by the full path of its test file, and in a deterministic build the expectation fails with:

Failure message
Expected that description
matches the snapshot "/_/Tests/AlbumTests.Describes.awexpect-snapshot.txt",
but the snapshot could not be read: The path "/_/Tests/AlbumTests.cs" comes from a deterministic build, but the test assembly records no source root for it, which the build targets of aweXpect.Snapshots add.
How the recorded path is found

The recorded path is registered when the test assembly is loaded, by a module initializer that the source generator of aweXpect.Core adds to the test project. From a test assembly that cannot compile a module initializer, e.g. for .NET Framework with C# 7.3 or in F#, it is read when a snapshot needs it, unless the ExcludedAssemblyPrefixes exclude the assembly, e.g. Microsoft.MyApp.Tests by the prefix Microsoft. The expectation then fails with a message that names the excluded assembly, so that you can remove the prefix that matches it.