Improve error message for migration extract and add tests (#1338)

src/main.rs

@@ -68,7 +68,15 @@ fn main() {
             if let Some(e) = err.downcast_ref::<edgedb_errors::Error>() {
                 print::edgedb_error(e, false);
             } else {
-                print::error(err);
+                let mut error_chain = err.chain();
+                if let Some(first) = error_chain.next() {
+                    print::error(first);
+                } else {
+                    print::error(" <empty error message>");
+                }
+                for e in error_chain {
+                    eprintln!("  Caused by: {e}");
+                }
             }
             for item in err.chain() {
                 if let Some(e) = item.downcast_ref::<hint::HintedError>() {

src/migrations/extract.rs

@@ -1,5 +1,7 @@
+use anyhow::Context as _;
 use fs_err as fs;
 use std::iter::Once;
+use std::path::Path;
 
 use crate::commands::{ExitCode, Options};
 use crate::connect::Connection;
@@ -126,14 +128,33 @@ pub async fn extract(
         }
     }
 
+    // make sure that migrations dir exists
+    let to_migrations_dir = src_ctx.schema_dir.join("migrations");
+    if !to_migrations_dir.is_dir() {
+        if src_ctx.schema_dir.is_dir() {
+            print::warn(format!(
+                "Creating directory {}",
+                to_migrations_dir.display()
+            ));
+            fs::create_dir(to_migrations_dir)?;
+        } else {
+            anyhow::bail!(
+                "Cannot write migrations because path {} is not a directory",
+                src_ctx.schema_dir.display()
+            );
+        }
+    }
+
+    // copy migration files
     let mut updated = false;
     for from in migration::read_names(&temp_ctx).await? {
         let to = src_ctx
             .schema_dir
             .join("migrations")
             .join(from.file_name().expect(""));
         print::success_msg("Writing", to.display());
-        fs::copy(from, to)?;
+        fs::copy(from, &to)
+            .with_context(|| format!("Cannot write {}", relative_to_current_dir(&to).display()))?;
         updated = true;
     }
     for path in to_delete {
@@ -149,3 +170,13 @@ pub async fn extract(
     }
     Ok(())
 }
+
+fn relative_to_current_dir(path: &Path) -> &Path {
+    let curr_dir = std::env::current_dir().ok();
+
+    if let Some(stripped) = curr_dir.and_then(|wd| path.strip_prefix(&wd).ok()) {
+        stripped
+    } else {
+        path
+    }
+}

tests/func/migrations.rs

@@ -1,4 +1,4 @@
-use crate::SERVER;
+use crate::{rm_migration_files, SERVER};
 use predicates::boolean::PredicateBooleanExt;
 use predicates::str::{contains, ends_with};
 use std::fs;
@@ -720,6 +720,77 @@ fn modified1() {
         );
 }
 
+#[test]
+fn extract01() {
+    SERVER
+        .admin_cmd()
+        .arg("branch")
+        .arg("create")
+        .arg("extract01")
+        .arg("--empty")
+        .assert()
+        .success();
+    SERVER
+        .admin_cmd()
+        .arg("--branch=extract01")
+        .arg("query")
+        .arg(
+            r#"
+            start migration to { module default { type X; } };
+            populate migration;
+            commit migration;
+            "#,
+        )
+        .assert()
+        .success();
+
+    // no migrations dir, needs to create
+    fs::remove_dir_all("tests/migrations/db1/extract01/migrations").ok();
+    SERVER
+        .admin_cmd()
+        .arg("--branch=extract01")
+        .arg("migration")
+        .arg("extract")
+        .arg("--schema-dir=tests/migrations/db1/extract01")
+        .assert()
+        .success()
+        .stderr(contains("Creating directory").and(contains("Writing")));
+
+    // base case
+    rm_migration_files("tests/migrations/db1/extract01", &[1]);
+    SERVER
+        .admin_cmd()
+        .arg("--branch=extract01")
+        .arg("migration")
+        .arg("extract")
+        .arg("--schema-dir=tests/migrations/db1/extract01")
+        .assert()
+        .success()
+        .stderr(contains("Writing"));
+
+    // test error printing
+    rm_migration_files("tests/migrations/db1/extract01", &[1]);
+    let mut perm = fs::metadata("tests/migrations/db1/extract01/migrations")
+        .unwrap()
+        .permissions();
+    perm.set_readonly(true);
+    fs::set_permissions("tests/migrations/db1/extract01/migrations", perm).unwrap();
+    SERVER
+        .admin_cmd()
+        .arg("--branch=extract01")
+        .arg("migration")
+        .arg("extract")
+        .arg("--schema-dir=tests/migrations/db1/extract01")
+        .assert()
+        .failure()
+        .stderr(
+            contains("Writing")
+                .and(contains("edgedb error: Cannot write"))
+                .and(contains("\n  Caused by: failed to copy file from"))
+                .and(contains("\n  Caused by: Permission denied")),
+        );
+}
+
 #[test]
 fn error() {
     SERVER

tests/migrations/db1/extract01/default.esdl

@@ -0,0 +1,5 @@
+module default {
+    type Type1 {
+        property field1 -> str;
+    };
+};