fix extra spacing (#1149)

ethers-solc/src/config.rs

@@ -311,7 +311,7 @@ impl ProjectPathsConfig {
         for import in imports.iter() {
             let import_path = self.resolve_import(target_dir, import.data())?;
             let s = self.flatten_node(&import_path, graph, imported, true, true, true)?;
-            let import_content = s.trim().as_bytes();
+            let import_content = s.as_bytes();
             let import_content_len = import_content.len() as isize;
             let (start, end) = import.loc_by_offset(offset);
             content.splice(start..end, import_content.iter().copied());
@@ -321,6 +321,7 @@ impl ProjectPathsConfig {
         let result = String::from_utf8(content).map_err(|err| {
             SolcError::msg(format!("failed to convert extended bytes to string: {}", err))
         })?;
+        let result = utils::RE_THREE_OR_MORE_NEWLINES.replace_all(&result, "\n\n").into_owned();
 
         Ok(result)
     }

ethers-solc/src/utils.rs

@@ -32,6 +32,9 @@ pub static RE_SOL_PRAGMA_VERSION: Lazy<Regex> =
 pub static RE_SOL_SDPX_LICENSE_IDENTIFIER: Lazy<Regex> =
     Lazy::new(|| Regex::new(r"///?\s*SPDX-License-Identifier:\s*(?P<license>.+)").unwrap());
 
+/// A regex used to remove extra lines in flatenned files
+pub static RE_THREE_OR_MORE_NEWLINES: Lazy<Regex> = Lazy::new(|| Regex::new("\n{3,}").unwrap());
+
 /// Returns all path parts from any solidity import statement in a string,
 /// `import "./contracts/Contract.sol";` -> `"./contracts/Contract.sol"`.
 ///

ethers-solc/tests/project.rs

@@ -492,8 +492,11 @@ contract C { }
         result,
         r#"
 pragma solidity ^0.8.10;
+
 contract C { }
+
 contract B { }
+
 contract A { }
 "#
     );
@@ -547,8 +550,11 @@ contract C { }
         r#"
 pragma solidity ^0.8.10;
 pragma experimental ABIEncoderV2;
+
 contract C { }
+
 contract B { }
+
 contract A { }
 "#
     );
@@ -572,6 +578,7 @@ fn can_flatten_file_with_duplicates() {
 pragma solidity >=0.6.0;
 
 contract Bar {}
+
 contract Foo {}
 
 contract FooBar {}
@@ -598,6 +605,7 @@ fn can_flatten_on_solang_failure() {
 pragma solidity ^0.8.10;
 
 library Lib {}
+
 // Intentionally erroneous code
 contract Contract {
     failure();
@@ -650,9 +658,64 @@ contract C { }
     assert_eq!(
         result.trim(),
         r#"pragma solidity ^0.8.10;
+
 contract C { }
+
 error IllegalArgument();
 error IllegalState();
+
+contract A { }"#
+    );
+}
+
+#[test]
+fn can_flatten_remove_extra_spacing() {
+    let project = TempProject::dapptools().unwrap();
+
+    let f = project
+        .add_source(
+            "A",
+            r#"pragma solidity ^0.8.10;
+import "./C.sol";
+import "./B.sol";
+contract A { }
+"#,
+        )
+        .unwrap();
+
+    project
+        .add_source(
+            "B",
+            r#"// This is a B Contract
+pragma solidity ^0.8.10;
+
+import "./C.sol";
+
+contract B { }
+"#,
+        )
+        .unwrap();
+
+    project
+        .add_source(
+            "C",
+            r#"pragma solidity ^0.8.10;
+contract C { }
+"#,
+        )
+        .unwrap();
+
+    let result = project.flatten(&f).unwrap();
+    assert_eq!(
+        result.trim(),
+        r#"pragma solidity ^0.8.10;
+
+contract C { }
+
+// This is a B Contract
+
+contract B { }
+
 contract A { }"#
     );
 }