remove #[cfg(test)] #236

Job	Run time
Book tests	2m 20s
Build target wasm32-unknown-unknown	2m 24s
Intra-doc links	2m 24s
Bitrot check	1m 16s
Build target wasm32-wasi	2m 21s
Rustfmt	14s
Test on ubuntu-latest	4m 23s
Test on i686-unknown-linux-gnu	4m 23s
Test on windows-latest	4m 19s
Test on macOS-latest	23s
Test on i686-unknown-linux-gnu with beta features	4m 4s
Test on ubuntu-latest with beta features	4m 22s
Test on i686-unknown-linux-gnu with nightly features	4m 22s
Test on windows-latest with beta features	4m 27s
Test on macOS-latest with beta features	4m 24s
Test on ubuntu-latest with nightly features	4m 27s
Test on windows-latest with nightly features	4m 27s
Test on macOS-latest with nightly features	4m 28s
	59m 28s

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