Add tests for crate_to_bp_modules.

Bug: 293289578
Test: atest cargo_embargo.test
Change-Id: I9063a2dffea3a716224a1bd6a722e408b5eb0494

tools/cargo_embargo/Android.bp

@@ -16,8 +16,8 @@ package {
     default_applicable_licenses: ["Android-Apache-2.0"],
 }
 
-rust_binary_host {
-    name: "cargo_embargo",
+rust_defaults {
+    name: "cargo_embargo.defaults",
     srcs: ["src/main.rs"],
     // Disable LTO for faster builds. Don't need the performance here.
     flags: ["-C lto=off"],
@@ -31,3 +31,13 @@ rust_binary_host {
         "libserde_json",
     ],
 }
+
+rust_binary_host {
+    name: "cargo_embargo",
+    defaults: ["cargo_embargo.defaults"],
+}
+
+rust_test_host {
+    name: "cargo_embargo.test",
+    defaults: ["cargo_embargo.defaults"],
+}

tools/cargo_embargo/src/bp.rs

@@ -16,16 +16,16 @@ use anyhow::Result;
 use std::collections::BTreeMap;
 
 /// Build module.
-#[derive(Clone, PartialEq, Eq, PartialOrd, Ord)]
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
 pub struct BpModule {
-    module_type: String,
+    pub module_type: String,
     pub props: BpProperties,
 }
 
 /// Properties of a build module, or of a nested object value.
-#[derive(Clone, PartialEq, Eq, PartialOrd, Ord)]
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
 pub struct BpProperties {
-    map: BTreeMap<String, BpValue>,
+    pub map: BTreeMap<String, BpValue>,
     /// A raw block of text to append after the last key-value pair, but before the closing brace.
     /// For example, if you have the properties
     ///
@@ -44,7 +44,7 @@ pub struct BpProperties {
     pub raw_block: Option<String>,
 }
 
-#[derive(Clone, PartialEq, Eq, PartialOrd, Ord)]
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
 pub enum BpValue {
     Object(BpProperties),
     Bool(bool),

tools/cargo_embargo/src/config.rs

@@ -29,7 +29,7 @@ fn default_true() -> bool {
 }
 
 /// Options that apply to everything.
-#[derive(Deserialize)]
+#[derive(Default, Deserialize)]
 #[serde(deny_unknown_fields)]
 pub struct Config {
     /// Whether to output "rust_test" modules.

tools/cargo_embargo/src/main.rs

@@ -535,3 +535,58 @@ fn crate_to_bp_modules(
     }
     Ok(modules)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn crate_to_bp_empty() {
+        let c = Crate {
+            name: "name".to_string(),
+            package_name: "package_name".to_string(),
+            edition: "2021".to_string(),
+            types: vec![],
+            ..Default::default()
+        };
+        let cfg = Config { ..Default::default() };
+        let package_cfg = PackageConfig { ..Default::default() };
+        let modules = crate_to_bp_modules(&c, &cfg, &package_cfg, &[]).unwrap();
+
+        assert_eq!(modules, vec![]);
+    }
+
+    #[test]
+    fn crate_to_bp_minimal() {
+        let c = Crate {
+            name: "name".to_string(),
+            package_name: "package_name".to_string(),
+            edition: "2021".to_string(),
+            types: vec![CrateType::Lib],
+            ..Default::default()
+        };
+        let cfg = Config { ..Default::default() };
+        let package_cfg = PackageConfig { ..Default::default() };
+        let modules = crate_to_bp_modules(&c, &cfg, &package_cfg, &[]).unwrap();
+
+        assert_eq!(
+            modules,
+            vec![BpModule {
+                module_type: "rust_library".to_string(),
+                props: BpProperties {
+                    map: [
+                        ("cargo_env_compat".to_string(), BpValue::Bool(true)),
+                        ("crate_name".to_string(), BpValue::String("name".to_string())),
+                        ("edition".to_string(), BpValue::String("2021".to_string())),
+                        ("host_supported".to_string(), BpValue::Bool(true)),
+                        ("name".to_string(), BpValue::String("libname".to_string())),
+                        ("srcs".to_string(), BpValue::List(vec![BpValue::String("".to_string())])),
+                    ]
+                    .into_iter()
+                    .collect(),
+                    raw_block: None
+                }
+            }]
+        );
+    }
+}