[cargo-compare] add some comparison testing to CI

This works by:
* setting up a real, fairly complex fixture
* generating random queries using proptest
* running them through cargo and guppy
* ensuring that they produce the same results

Not only does this give us high confidence that cargo
and guppy produce the same results, it also gets us
most of the way to #83.

Most of the work in this commit is simply setting up
all the necessary test infrastructure. We piggy-back on
existing proptest infrastructure as much as possible.

fixtures/README.md

@@ -8,5 +8,7 @@ The fixtures are organized into several folders.
 
 * `small`: relatively simple examples that cover basic and some edge case functionality
 * `large`: complex examples pulled from real-world Rust repositories, that test a variety of edge cases
-* `invalid`: examples that are *representable* as cargo metadata (i.e. they are valid JSON and follow the general
-  schema) but are *invalid* in some way; `cargo metadata` should never be able to generate these
+* `invalid`: examples that are [*representable*](https://oleb.net/blog/2018/03/making-illegal-states-unrepresentable/)
+  as cargo metadata (i.e. they are valid JSON and follow the general schema) but are *invalid* in some way; `cargo
+  metadata` should never be able to generate these
+* `workspace`: real workspaces, used for comparison testing with Cargo

fixtures/workspace/inside-outside/external/.gitignore

@@ -0,0 +1,2 @@
+/target
+Cargo.lock

fixtures/workspace/inside-outside/external/Cargo.toml

@@ -0,0 +1,27 @@
+[package]
+name = "external"
+version = "0.1.0"
+authors = ["Fake Author <[email protected]>"]
+edition = "2018"
+
+[dependencies]
+transitive = { path = "../transitive" }
+bytes = { version = "0.5", optional = true }
+
+[dev-dependencies]
+transitive = { path = "../transitive", features = ["dev-feature"] }
+
+[build-dependencies]
+transitive = { path = "../transitive", features = ["build-feature"] }
+
+[features]
+internal-dev-feature = []
+internal-build-feature = []
+main-dev-feature = []
+main-build-feature = []
+macro-normal-feature = []
+macro-build-feature = []
+macro-dev-feature = []
+side-feature = ["bytes"]
+
+[workspace]

fixtures/workspace/inside-outside/external/src/lib.rs

@@ -0,0 +1,7 @@
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn it_works() {
+        assert_eq!(2 + 2, 4);
+    }
+}

fixtures/workspace/inside-outside/inactive/.gitignore

@@ -0,0 +1,2 @@
+/target
+Cargo.lock

fixtures/workspace/inside-outside/inactive/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "inactive"
+version = "0.1.0"
+authors = ["Fake Author <[email protected]>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+transitive = { path = "../transitive", features = ["inactive-normal"] }
+
+[build-dependencies]
+transitive = { path = "../transitive", features = ["inactive-build"] }
+
+[dev-dependencies]
+transitive = { path = "../transitive", features = ["inactive-dev"] }
+
+[features]
+extra = ["transitive/extra"]
+
+[workspace]

fixtures/workspace/inside-outside/inactive/src/lib.rs

@@ -0,0 +1,7 @@
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn it_works() {
+        assert_eq!(2 + 2, 4);
+    }
+}

fixtures/workspace/inside-outside/transitive/.gitignore

@@ -0,0 +1,2 @@
+/target
+Cargo.lock

fixtures/workspace/inside-outside/transitive/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "transitive"
+version = "0.1.0"
+authors = ["Fake Author <[email protected]>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[features]
+build-feature = []
+dev-feature = []
+inactive-normal = []
+inactive-build = []
+inactive-dev = []
+extra = []
+
+[workspace]

fixtures/workspace/inside-outside/transitive/src/lib.rs

@@ -0,0 +1,7 @@
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn it_works() {
+        assert_eq!(2 + 2, 4);
+    }
+}

fixtures/workspace/inside-outside/workspace/.gitignore

@@ -0,0 +1 @@
+/target

fixtures/workspace/inside-outside/workspace/Cargo.toml

@@ -0,0 +1,2 @@
+[workspace]
+members = ["main", "internal", "internal-macro", "side"]

fixtures/workspace/inside-outside/workspace/internal-macro/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "internal-macro"
+version = "0.1.0"
+authors = ["Fake Author <[email protected]>"]
+edition = "2018"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+external = { path = "../../external", features = ["macro-normal-feature"] }
+
+[build-dependencies]
+external = { path = "../../external", features = ["macro-build-feature"] }
+
+[dev-dependencies]
+external = { path = "../../external", features = ["macro-dev-feature"] }
+
+[features]
+main-build-feature = []
+internal-normal-feature = []

fixtures/workspace/inside-outside/workspace/internal-macro/src/lib.rs

@@ -0,0 +1,7 @@
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn it_works() {
+        assert_eq!(2 + 2, 4);
+    }
+}

fixtures/workspace/inside-outside/workspace/internal/Cargo.toml

@@ -0,0 +1,24 @@
+[package]
+name = "internal"
+version = "0.1.0"
+authors = ["Fake Author <[email protected]>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+lazy_static = "1"
+external = { path = "../../external" }
+internal-macro = { path = "../internal-macro", features = ["internal-normal-feature"] }
+
+[dev-dependencies]
+lazy_static = {version = "1", features = ["spin"] }
+bytes = "0.5"
+external = { path = "../../external", features = ["internal-dev-feature"] }
+
+[build-dependencies]
+external = { path = "../../external", features = ["internal-build-feature"] }
+
+[features]
+dev-feature = []
+build-feature = []

fixtures/workspace/inside-outside/workspace/internal/src/lib.rs

@@ -0,0 +1,7 @@
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn it_works() {
+        assert_eq!(2 + 2, 4);
+    }
+}

fixtures/workspace/inside-outside/workspace/main/Cargo.toml

@@ -0,0 +1,27 @@
+[package]
+name = "main"
+version = "0.1.0"
+authors = ["Fake Author <[email protected]>"]
+edition = "2018"
+build = "build.rs"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+external = { path = "../../external" }
+internal = { path = "../internal" }
+
+[build-dependencies]
+external = { path = "../../external", features = ["main-build-feature"] }
+internal = { path = "../internal", features = ["build-feature"] }
+internal-macro = { path = "../internal-macro", features = ["main-build-feature"] }
+
+[dev-dependencies]
+external = { path = "../../external", features = ["main-dev-feature"] }
+internal = { path = "../internal", features = ["dev-feature"] }
+
+[target.'cfg(all(unix, not(unix)))'.build-dependencies]
+inactive = { path = "../../inactive" }
+
+[features]
+inactive-extra = ["inactive/extra"]

fixtures/workspace/inside-outside/workspace/main/build.rs

@@ -0,0 +1,2 @@
+fn main() {
+}

fixtures/workspace/inside-outside/workspace/main/src/lib.rs

@@ -0,0 +1,7 @@
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn it_works() {
+        assert_eq!(2 + 2, 4);
+    }
+}

fixtures/workspace/inside-outside/workspace/side/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "side"
+version = "0.1.0"
+authors = ["Fake Author <[email protected]>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+external = { path = "../../external", features = ["side-feature"] }

fixtures/workspace/inside-outside/workspace/side/src/lib.rs

@@ -0,0 +1,7 @@
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn it_works() {
+        assert_eq!(2 + 2, 4);
+    }
+}