test: add edge case tests for sources ordering

- Empty sources
- Single source file
- Non-sequential IDs with gaps (5, 50, 100)
- Roundtrip serialization/deserialization
- Many sources (50 files)

Author: gakonst

crates/compilers/src/buildinfo.rs

@@ -179,4 +179,140 @@ mod tests {
             "m_middle.sol (id=1) should appear before a_first.sol (id=2) in output.sources"
         );
     }
+
+    #[test]
+    fn sources_ordering_empty() {
+        let v: Version = "0.8.4+commit.c7e474f2".parse().unwrap();
+        let input = SolcVersionedInput::build(
+            Sources::new(),
+            Default::default(),
+            SolcLanguage::Solidity,
+            v,
+        );
+
+        let output = CompilerOutput::<Error, Contract>::default();
+        let raw_info = RawBuildInfo::new(&input, &output, true).unwrap();
+        let json_str = serde_json::to_string(&raw_info).unwrap();
+
+        assert!(json_str.contains(r#""sources":{}"#));
+    }
+
+    #[test]
+    fn sources_ordering_single_source() {
+        let v: Version = "0.8.4+commit.c7e474f2".parse().unwrap();
+        let input = SolcVersionedInput::build(
+            Sources::from([(PathBuf::from("only.sol"), Source::new(""))]),
+            Default::default(),
+            SolcLanguage::Solidity,
+            v,
+        );
+
+        let mut output = CompilerOutput::<Error, Contract>::default();
+        output.sources.insert(PathBuf::from("only.sol"), SourceFile { id: 42, ast: None });
+
+        let raw_info = RawBuildInfo::new(&input, &output, true).unwrap();
+        let json_str = serde_json::to_string(&raw_info).unwrap();
+
+        assert!(json_str.contains(r#""only.sol":{"id":42"#));
+    }
+
+    #[test]
+    fn sources_ordering_with_gaps_in_ids() {
+        let v: Version = "0.8.4+commit.c7e474f2".parse().unwrap();
+        let input = SolcVersionedInput::build(
+            Sources::from([
+                (PathBuf::from("a.sol"), Source::new("")),
+                (PathBuf::from("b.sol"), Source::new("")),
+                (PathBuf::from("c.sol"), Source::new("")),
+            ]),
+            Default::default(),
+            SolcLanguage::Solidity,
+            v,
+        );
+
+        let mut output = CompilerOutput::<Error, Contract>::default();
+        output.sources.insert(PathBuf::from("a.sol"), SourceFile { id: 100, ast: None });
+        output.sources.insert(PathBuf::from("b.sol"), SourceFile { id: 5, ast: None });
+        output.sources.insert(PathBuf::from("c.sol"), SourceFile { id: 50, ast: None });
+
+        let raw_info = RawBuildInfo::new(&input, &output, true).unwrap();
+        let json_str = serde_json::to_string(&raw_info).unwrap();
+
+        let output_start = json_str.find(r#""output":"#).unwrap();
+        let output_section = &json_str[output_start..];
+
+        let b_pos = output_section.find("b.sol").unwrap();
+        let c_pos = output_section.find("c.sol").unwrap();
+        let a_pos = output_section.find("a.sol").unwrap();
+
+        assert!(b_pos < c_pos, "b.sol (id=5) should appear before c.sol (id=50)");
+        assert!(c_pos < a_pos, "c.sol (id=50) should appear before a.sol (id=100)");
+    }
+
+    #[test]
+    fn sources_ordering_roundtrip() {
+        let v: Version = "0.8.4+commit.c7e474f2".parse().unwrap();
+        let input = SolcVersionedInput::build(
+            Sources::from([
+                (PathBuf::from("z.sol"), Source::new("")),
+                (PathBuf::from("a.sol"), Source::new("")),
+            ]),
+            Default::default(),
+            SolcLanguage::Solidity,
+            v,
+        );
+
+        let mut output = CompilerOutput::<Error, Contract>::default();
+        output.sources.insert(PathBuf::from("z.sol"), SourceFile { id: 0, ast: None });
+        output.sources.insert(PathBuf::from("a.sol"), SourceFile { id: 1, ast: None });
+
+        let raw_info = RawBuildInfo::new(&input, &output, true).unwrap();
+        let json_str = serde_json::to_string(&raw_info).unwrap();
+
+        let parsed: BuildInfo<SolcVersionedInput, CompilerOutput<Error, Contract>> =
+            serde_json::from_str(&json_str).unwrap();
+
+        assert_eq!(parsed.output.sources.len(), 2);
+        assert_eq!(parsed.output.sources.get(&PathBuf::from("z.sol")).unwrap().id, 0);
+        assert_eq!(parsed.output.sources.get(&PathBuf::from("a.sol")).unwrap().id, 1);
+    }
+
+    #[test]
+    fn sources_ordering_many_sources() {
+        let v: Version = "0.8.4+commit.c7e474f2".parse().unwrap();
+
+        let sources: Sources = (0..50)
+            .map(|i| (PathBuf::from(format!("contract_{:02}.sol", 49 - i)), Source::new("")))
+            .collect();
+
+        let input =
+            SolcVersionedInput::build(sources, Default::default(), SolcLanguage::Solidity, v);
+
+        let mut output = CompilerOutput::<Error, Contract>::default();
+        for i in 0..50u32 {
+            output.sources.insert(
+                PathBuf::from(format!("contract_{:02}.sol", 49 - i)),
+                SourceFile { id: i, ast: None },
+            );
+        }
+
+        let raw_info = RawBuildInfo::new(&input, &output, true).unwrap();
+        let json_str = serde_json::to_string(&raw_info).unwrap();
+
+        let output_start = json_str.find(r#""output":"#).unwrap();
+        let output_section = &json_str[output_start..];
+
+        let mut last_pos = 0;
+        for i in 0..50 {
+            let filename = format!("contract_{:02}.sol", 49 - i);
+            let pos = output_section.find(&filename).unwrap();
+            assert!(
+                pos > last_pos || i == 0,
+                "Sources should be ordered by ID: {} (id={}) at wrong position",
+                filename,
+                i
+            );
+            last_pos = pos;
+        }
+    }
 }