Add test for cargo_common_metadata

Fix missing `authors` entry in the provided example

clippy_lints/src/cargo_common_metadata.rs

@@ -23,6 +23,7 @@ declare_clippy_lint! {
     /// [package]
     /// name = "clippy"
     /// version = "0.0.212"
+    /// authors = ["Someone <someone@rust-lang.org>"]
     /// description = "A bunch of helpful lints to avoid common pitfalls in Rust"
     /// repository = "https://github.com/rust-lang/rust-clippy"
     /// readme = "README.md"

tests/ui-cargo/cargo_common_metadata/fail/Cargo.toml

@@ -0,0 +1,3 @@
+[package]
+name = "cargo_common_metadata"
+version = "0.1.0"

tests/ui-cargo/cargo_common_metadata/fail/src/main.rs

@@ -0,0 +1,3 @@
+#![warn(clippy::cargo_common_metadata)]
+
+fn main() {}

tests/ui-cargo/cargo_common_metadata/fail/src/main.stderr

@@ -0,0 +1,18 @@
+error: package `cargo_common_metadata` is missing `package.authors` metadata
+   |
+   = note: `-D clippy::cargo-common-metadata` implied by `-D warnings`
+
+error: package `cargo_common_metadata` is missing `package.description` metadata
+
+error: package `cargo_common_metadata` is missing `either package.license or package.license_file` metadata
+
+error: package `cargo_common_metadata` is missing `package.repository` metadata
+
+error: package `cargo_common_metadata` is missing `package.readme` metadata
+
+error: package `cargo_common_metadata` is missing `package.keywords` metadata
+
+error: package `cargo_common_metadata` is missing `package.categories` metadata
+
+error: aborting due to 7 previous errors
+

tests/ui-cargo/cargo_common_metadata/pass/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "cargo_common_metadata"
+version = "0.1.0"
+authors = ["Random person from the Internet <someone@someplace.org>"]
+description = "A test package for the cargo_common_metadata lint"
+repository = "https://github.com/someone/cargo_common_metadata"
+readme = "README.md"
+license = "MIT OR Apache-2.0"
+keywords = ["metadata", "lint", "clippy"]
+categories = ["development-tools::testing"]

tests/ui-cargo/cargo_common_metadata/pass/src/main.rs

@@ -0,0 +1,3 @@
+#![warn(clippy::cargo_common_metadata)]
+
+fn main() {}