1 files changed, 144 insertions, 0 deletions
diff --git a/src/tools/cargo/tests/testsuite/messages.rs b/src/tools/cargo/tests/testsuite/messages.rs
new file mode 100644
index 000000000..2c534d8f0
--- /dev/null
+++ b/src/tools/cargo/tests/testsuite/messages.rs
@@ -0,0 +1,144 @@
+//! General tests specifically about diagnostics and other messages.
+//!
+//! Tests for message caching can be found in `cache_messages`.
+
+use cargo_test_support::{process, project, Project};
+use cargo_util::ProcessError;
+
+/// Captures the actual diagnostics displayed by rustc. This is done to avoid
+/// relying on the exact message formatting in rustc.
+pub fn raw_rustc_output(project: &Project, path: &str, extra: &[&str]) -> String {
+    let mut proc = process("rustc");
+    if cfg!(windows) {
+        // Sanitize in case the caller wants to do direct string comparison with Cargo's output.
+        proc.arg(path.replace('/', "\\"));
+    } else {
+        proc.arg(path);
+    }
+    let rustc_output = match proc
+        .arg("--crate-type=lib")
+        .args(extra)
+        .cwd(project.root())
+        .exec_with_output()
+    {
+        Ok(output) => output.stderr,
+        Err(e) => e.downcast::<ProcessError>().unwrap().stderr.unwrap(),
+    };
+    // Do a little dance to remove rustc's "warnings emitted" message and the subsequent newline.
+    let stderr = std::str::from_utf8(&rustc_output).expect("utf8");
+    let mut lines = stderr.lines();
+    let mut result = String::new();
+    while let Some(line) = lines.next() {
+        if line.contains("warning emitted")
+            || line.contains("warnings emitted")
+            || line.contains("aborting due to")
+        {
+            // Eat blank line.
+            match lines.next() {
+                None | Some("") => continue,
+                Some(s) => panic!("unexpected str {}", s),
+            }
+        }
+        result.push_str(line);
+        result.push('\n');
+    }
+    result
+}
+
+#[cargo_test]
+fn deduplicate_messages_basic() {
+    let p = project()
+        .file(
+            "src/lib.rs",
+            r#"
+                pub fn foo() {
+                    let x = 1;
+                }
+            "#,
+        )
+        .build();
+    let rustc_message = raw_rustc_output(&p, "src/lib.rs", &[]);
+    let expected_output = format!(
+        "{}\
+warning: `foo` (lib) generated 1 warning (run `cargo fix --lib -p foo` to apply 1 suggestion)
+warning: `foo` (lib test) generated 1 warning (1 duplicate)
+[FINISHED] [..]
+[EXECUTABLE] unittests src/lib.rs (target/debug/deps/foo-[..][EXE])
+",
+        rustc_message
+    );
+    p.cargo("test --no-run -j1")
+        .with_stderr(&format!("[COMPILING] foo [..]\n{}", expected_output))
+        .run();
+    // Run again, to check for caching behavior.
+    p.cargo("test --no-run -j1")
+        .with_stderr(expected_output)
+        .run();
+}
+
+#[cargo_test]
+fn deduplicate_messages_mismatched_warnings() {
+    // One execution prints 1 warning, the other prints 2 where there is an overlap.
+    let p = project()
+        .file(
+            "src/lib.rs",
+            r#"
+                pub fn foo() {
+                    let x = 1;
+                }
+
+                #[test]
+                fn t1() {
+                    let MY_VALUE = 1;
+                    assert_eq!(MY_VALUE, 1);
+                }
+            "#,
+        )
+        .build();
+    let lib_output = raw_rustc_output(&p, "src/lib.rs", &[]);
+    let mut lib_test_output = raw_rustc_output(&p, "src/lib.rs", &["--test"]);
+    // Remove the duplicate warning.
+    let start = lib_test_output.find(&lib_output).expect("same warning");
+    lib_test_output.replace_range(start..start + lib_output.len(), "");
+    let expected_output = format!(
+        "\
+{}\
+warning: `foo` (lib) generated 1 warning (run `cargo fix --lib -p foo` to apply 1 suggestion)
+{}\
+warning: `foo` (lib test) generated 2 warnings (1 duplicate)
+[FINISHED] [..]
+[EXECUTABLE] unittests src/lib.rs (target/debug/deps/foo-[..][EXE])
+",
+        lib_output, lib_test_output
+    );
+    p.cargo("test --no-run -j1")
+        .with_stderr(&format!("[COMPILING] foo v0.0.1 [..]\n{}", expected_output))
+        .run();
+    // Run again, to check for caching behavior.
+    p.cargo("test --no-run -j1")
+        .with_stderr(expected_output)
+        .run();
+}
+
+#[cargo_test]
+fn deduplicate_errors() {
+    let p = project()
+        .file(
+            "src/lib.rs",
+            r#"
+                this should not compile
+            "#,
+        )
+        .build();
+    let rustc_message = raw_rustc_output(&p, "src/lib.rs", &[]);
+    p.cargo("test -j1")
+        .with_status(101)
+        .with_stderr(&format!(
+            "\
+[COMPILING] foo v0.0.1 [..]
+{}error: could not compile `foo` (lib) due to previous error
+",
+            rustc_message
+        ))
+        .run();
+}