anchor test reports target/idl/x.json doesn't exist after a successful build: add idl-build feature on Anchor 0.30+
Symptom: anchor build and anchor deploy both report success, but anchor test dies before any test body runs:
Error: target/idl/web_3_meet_program.json doesn't exist. Did you run anchor build?
at Object.get (.../@coral-xyz/anchor/src/workspace.ts:64:15)
The stack trace is from anchor.workspace.<Program> resolution in the test file, so it looks like a path or naming problem, and re-running anchor build changes nothing.
Cause: as of Anchor 0.30, IDL generation moved into a dedicated cargo feature. If the program crate's Cargo.toml does not opt in, the build compiles and deploys fine but never emits target/idl/*.json, and the workspace loader then cannot find it. Add:
[features] idl-build = ["anchor-lang/idl-build"]
to the program's Cargo.toml (in programs/<name>/Cargo.toml, not the workspace root). If anchor-spl is in use, its idl-build feature belongs in the same list.
Second cause with the identical message: the IDL build is a separate compilation pass, so a program that builds for the SBF target can still fail the IDL pass — for example on types Anchor cannot represent. That failure is easy to scroll past in the build output, leaving the same missing-file error. Re-read the full anchor build log for errors after the SBF artifacts are produced.
The wrong guess is renaming the program or the test import to match the file, or deleting target/ and rebuilding. Neither creates an IDL that was never generated. Also verify the Anchor.toml and declare_id! program name matches the snake_cased file name Anchor expects.
Source: adapted from a Stack Exchange answer by Jonas H. (question by Sardar Ahmed Khan), https://solana.stackexchange.com/questions/15569/anchor-test-command-giving-me-error-no-such-file-or-directory-os-error-2 — CC BY-SA 4.0
The fix is right. Precision on the symptom, from reading anchor-cli v0.30.0/v0.30.1 cli/src/lib.rs (not run): generate_idl() checks the program manifest for an 'idl-build' feature and, if it's missing, returns an error with the exact fix text: '
idl-buildfeature is missing. To solve, add [features] idl-build = ["anchor-lang/idl-build", "anchor-spl/idl-build"] in <path>'. It adds the anchor-spl part automatically when anchor-spl is a dependency. The build path propagates that with '?', so a 0.30.x 'anchor build' does NOT report success. It fails after the SBF compile, and because target/deploy/*.so is already written, a following 'anchor deploy' works, which makes the build look fine. The one code path that skips IDL generation silently is 'anchor build --no-idl' ('if !no_idl'). If you see no IDL and no such error, check that 'anchor --version' matches anchor-lang in Cargo.lock. Changelog: #2824 ('cli: Require idl-build feature').