fix(coverage): separate dir + caching for coverage artifacts

crates/evm/coverage/src/analysis.rs

@@ -3,7 +3,7 @@ use alloy_primitives::map::HashMap;
 use foundry_common::TestFunctionExt;
 use foundry_compilers::artifacts::ast::{self, Ast, Node, NodeType};
 use rayon::prelude::*;
-use std::sync::Arc;
+use std::{borrow::Cow, sync::Arc};
 
 /// A visitor that walks the AST of a single contract and finds coverage items.
 #[derive(Clone, Debug)]
@@ -592,5 +592,5 @@ pub struct SourceFile<'a> {
     /// The source code.
     pub source: String,
     /// The AST of the source code.
-    pub ast: &'a Ast,
+    pub ast: Cow<'a, Ast>,
 }

crates/forge/bin/cmd/coverage.rs

@@ -23,6 +23,7 @@ use foundry_config::{Config, SolcReq};
 use rayon::prelude::*;
 use semver::Version;
 use std::{
+    borrow::Cow,
     path::{Path, PathBuf},
     sync::Arc,
 };
@@ -92,7 +93,28 @@ impl CoverageArgs {
     /// Builds the project.
     fn build(&self, config: &Config) -> Result<(Project, ProjectCompileOutput)> {
         // Set up the project
-        let mut project = config.create_project(false, false)?;
+        let mut project = config.create_project(config.cache, false)?;
+
+        // Set a different artifacts path for coverage. `out/coverage`.
+        // This is done to avoid overwriting the artifacts of the main build that maybe built with
+        // different optimizer settings or --via-ir. Optimizer settings are disabled for
+        // coverage builds.
+        let coverage_artifacts_path = project.artifacts_path().join("coverage");
+        project.paths.artifacts = coverage_artifacts_path.clone();
+        project.paths.build_infos = coverage_artifacts_path.join("build-info");
+
+        // Set a different compiler cache path for coverage. `cache/coverage`.
+        let cache_file = project
+            .paths
+            .cache
+            .components()
+            .last()
+            .ok_or_else(|| eyre::eyre!("Cache path is empty"))?;
+
+        let cache_dir =
+            project.paths.cache.parent().ok_or_else(|| eyre::eyre!("Cache path is empty"))?;
+        project.paths.cache = cache_dir.join("coverage").join(cache_file);
+
         if self.ir_minimum {
             // print warning message
             sh_warn!("{}", concat!(
@@ -124,6 +146,8 @@ impl CoverageArgs {
             project.settings.solc.via_ir = None;
         }
 
+        sh_warn!("optimizer settings have been disabled for accurate coverage reports")?;
+
         let output = ProjectCompiler::default()
             .compile(&project)?
             .with_stripped_file_prefixes(project.root());
@@ -139,28 +163,67 @@ impl CoverageArgs {
         // Collect source files.
         let project_paths = &project.paths;
         let mut versioned_sources = HashMap::<Version, SourceFiles<'_>>::default();
-        for (path, source_file, version) in output.output().sources.sources_with_version() {
-            report.add_source(version.clone(), source_file.id as usize, path.clone());
 
-            // Filter out dependencies
-            if !self.include_libs && project_paths.has_library_ancestor(path) {
-                continue;
-            }
+        if !output.output().sources.is_empty() {
+            // Freshly compiled sources
+            for (path, source_file, version) in output.output().sources.sources_with_version() {
+                report.add_source(version.clone(), source_file.id as usize, path.clone());
 
-            if let Some(ast) = &source_file.ast {
-                let file = project_paths.root.join(path);
-                trace!(root=?project_paths.root, ?file, "reading source file");
+                // Filter out dependencies
+                if !self.include_libs && project_paths.has_library_ancestor(path) {
+                    continue;
+                }
+
+                if let Some(ast) = &source_file.ast {
+                    let file = project_paths.root.join(path);
+                    trace!(root=?project_paths.root, ?file, "reading source file");
+
+                    let source = SourceFile {
+                        ast: Cow::Borrowed(ast),
+                        source: fs::read_to_string(&file)
+                            .wrap_err("Could not read source code for analysis")?,
+                    };
+                    versioned_sources
+                        .entry(version.clone())
+                        .or_default()
+                        .sources
+                        .insert(source_file.id as usize, source);
+                }
+            }
+        } else {
+            // Cached sources
+            for (id, artifact) in output.artifact_ids() {
+                // Filter out dependencies
+                if !self.include_libs && project_paths.has_library_ancestor(&id.source) {
+                    continue;
+                }
 
-                let source = SourceFile {
-                    ast,
-                    source: fs::read_to_string(&file)
-                        .wrap_err("Could not read source code for analysis")?,
+                let version = id.version;
+                let source_file = if let Some(source_file) = artifact.source_file() {
+                    source_file
+                } else {
+                    sh_warn!("ast source file not found for {}", id.source.display())?;
+                    continue;
                 };
-                versioned_sources
-                    .entry(version.clone())
-                    .or_default()
-                    .sources
-                    .insert(source_file.id as usize, source);
+
+                report.add_source(version.clone(), source_file.id as usize, id.source.clone());
+
+                if let Some(ast) = source_file.ast {
+                    let file = project_paths.root.join(id.source);
+                    trace!(root=?project_paths.root, ?file, "reading source file");
+
+                    let source = SourceFile {
+                        ast: Cow::Owned(ast),
+                        source: fs::read_to_string(&file)
+                            .wrap_err("Could not read source code for analysis")?,
+                    };
+
+                    versioned_sources
+                        .entry(version.clone())
+                        .or_default()
+                        .sources
+                        .insert(source_file.id as usize, source);
+                }
             }
         }
 

crates/forge/tests/cli/coverage.rs

@@ -1447,3 +1447,80 @@ contract AContract {
 
 "#]]);
 });
+
+forgetest!(test_diff_coverage_dir, |prj, cmd| {
+    prj.insert_ds_test();
+    prj.add_source(
+        "AContract.sol",
+        r#"
+contract AContract {
+    int public i;
+
+    function init() public {
+        i = 0;
+    }
+
+    function foo() public {
+        i = 1;
+    }
+}
+    "#,
+    )
+    .unwrap();
+
+    prj.add_source(
+        "AContractTest.sol",
+        r#"
+import "./test.sol";
+import {AContract} from "./AContract.sol";
+
+contract AContractTest is DSTest {
+    AContract a;
+
+    function setUp() public {
+        a = new AContract();
+        a.init();
+    }
+
+    function testFoo() public {
+        a.foo();
+    }
+}
+    "#,
+    )
+    .unwrap();
+
+    // forge build
+    cmd.arg("build").assert_success();
+
+    // forge coverage
+    // Assert 100% coverage (init function coverage called in setUp is accounted).
+    cmd.forge_fuse().arg("coverage").args(["--summary".to_string()]).assert_success().stdout_eq(
+        str![[r#"
+...
+| File              | % Lines       | % Statements  | % Branches    | % Funcs       |
+|-------------------|---------------|---------------|---------------|---------------|
+| src/AContract.sol | 100.00% (2/2) | 100.00% (2/2) | 100.00% (0/0) | 100.00% (2/2) |
+| Total             | 100.00% (2/2) | 100.00% (2/2) | 100.00% (0/0) | 100.00% (2/2) |
+
+"#]],
+    );
+
+    // forge build - Should not compile the contracts again.
+    cmd.forge_fuse().arg("build").assert_success().stdout_eq(
+        r#"No files changed, compilation skipped
+"#,
+    );
+
+    // forge coverage - Should not compile the contracts again.
+    cmd.forge_fuse().arg("coverage").args(["--summary".to_string()]).assert_success().stdout_eq(
+        str![[r#"No files changed, compilation skipped
+...
+| File              | % Lines       | % Statements  | % Branches    | % Funcs       |
+|-------------------|---------------|---------------|---------------|---------------|
+| src/AContract.sol | 100.00% (2/2) | 100.00% (2/2) | 100.00% (0/0) | 100.00% (2/2) |
+| Total             | 100.00% (2/2) | 100.00% (2/2) | 100.00% (0/0) | 100.00% (2/2) |
+
+"#]],
+    );
+});