Document the `harness` manifest option.

Add documentation for the `harness` manifest option, introduced in a6589681351dc4a87b6fc268d47b7d608004b455.

diff --git a/src/doc/manifest.md b/src/doc/manifest.md
index abb02f4d263c8458951b9c22334a402bdc38ba6c..025a8e2cbd6b0ffefb51ab7973555b77f92417e3 100644 (file)
--- a/src/doc/manifest.md
+++ b/src/doc/manifest.md
@@ -425,6 +425,11 @@ doc = true
 # If the target is meant to be a compiler plugin, this field must be set to true
 # for cargo to correctly compile it and make it available for all dependencies.
 plugin = false
+
+# If set to false, `cargo test` will omit the --test flag to rustc, which stops
+# it from generating a test harness. This is useful when the binary being built
+# manages the test runner itself.
+harness = true
 ```
 
 # Building Dynamic or Static Libraries