Add a "config" command with "get" and "list" subcommands

Partially fixes jj-vcs#531.

src/cli_util.rs

@@ -1221,6 +1221,26 @@ pub fn write_commit_summary(
     Ok(())
 }
 
+pub fn write_config_entry(
+    ui: &mut Ui,
+    path: &str,
+    value: config::Value,
+) -> Result<(), CommandError> {
+    match value.kind {
+        config::ValueKind::Table(table) => {
+            for (key, table_val) in table {
+                let key_path = match path {
+                    "" => key,
+                    _ => format!("{path}.{key}"),
+                };
+                write_config_entry(ui, key_path.as_str(), table_val)?;
+            }
+        }
+        _ => writeln!(ui, "{path}={value}")?,
+    };
+    Ok(())
+}
+
 pub fn short_commit_description(commit: &Commit) -> String {
     let first_line = commit.description().split('\n').next().unwrap();
     format!("{} ({})", short_commit_hash(commit.id()), first_line)

src/commands.rs

@@ -26,6 +26,7 @@ use std::{fs, io};
 use chrono::{FixedOffset, LocalResult, TimeZone, Utc};
 use clap::builder::NonEmptyStringValueParser;
 use clap::{ArgGroup, ArgMatches, CommandFactory, FromArgMatches, Subcommand};
+use config::Source;
 use itertools::Itertools;
 use jujutsu_lib::backend::{CommitId, Timestamp, TreeValue};
 use jujutsu_lib::commit::Commit;
@@ -54,7 +55,8 @@ use pest::Parser;
 use crate::cli_util::{
     check_stale_working_copy, print_checkout_stats, print_failed_git_export, resolve_base_revs,
     short_commit_description, short_commit_hash, user_error, user_error_with_hint,
-    write_commit_summary, Args, CommandError, CommandHelper, RevisionArg, WorkspaceCommandHelper,
+    write_commit_summary, write_config_entry, Args, CommandError, CommandHelper, RevisionArg,
+    WorkspaceCommandHelper,
 };
 use crate::config::FullCommandArgs;
 use crate::diff_util::{self, DiffFormat, DiffFormatArgs};
@@ -69,6 +71,8 @@ use crate::ui::Ui;
 enum Commands {
     Version(VersionArgs),
     Init(InitArgs),
+    #[command(subcommand)]
+    Config(ConfigSubcommand),
     Checkout(CheckoutArgs),
     Untrack(UntrackArgs),
     Files(FilesArgs),
@@ -142,6 +146,33 @@ struct InitArgs {
     git_repo: Option<String>,
 }
 
+/// Get config options
+///
+/// Operates on jj configuration, which comes from the config file and
+/// environment variables. Uses the config file at ~/.jjconfig.toml or
+/// $XDG_CONFIG_HOME/jj/config.toml, unless overridden with the JJ_CONFIG
+/// environment variable.
+///
+/// For supported config options and more details about jj config, see
+/// https://github.com/martinvonz/jj/blob/main/docs/config.md.
+///
+/// Note: Currently only supports getting config options, but support for
+/// setting options is also planned (see
+/// https://github.com/martinvonz/jj/issues/531).
+#[derive(clap::Subcommand, Clone, Debug)]
+enum ConfigSubcommand {
+    /// Get the value for a given key.
+    Get {
+        /// The config option name
+        #[arg(required = true, value_parser=NonEmptyStringValueParser::new())]
+        name: String,
+    },
+
+    /// List all variables set in config file, along with their values.
+    #[command(visible_alias("l"))]
+    List {},
+}
+
 /// Create a new, empty change and edit it in the working copy
 ///
 /// For more information, see
@@ -1156,6 +1187,35 @@ Set `ui.allow-init-native` to allow initializing a repo with the native backend.
     Ok(())
 }
 
+fn cmd_config(
+    ui: &mut Ui,
+    _command: &CommandHelper,
+    subcommand: &ConfigSubcommand,
+) -> Result<(), CommandError> {
+    ui.request_pager();
+    match subcommand {
+        ConfigSubcommand::Get { name } => {
+            let raw_value = ui.settings().config().get::<config::Value>(name);
+            let value = raw_value.map_err(|e| match e {
+                config::ConfigError::NotFound { .. } => user_error("key not found in config"),
+                _ => e.into(),
+            })?;
+            match value.kind {
+                config::ValueKind::Table(table) => {
+                    write_config_entry(ui, &name.to_string(), table.into())?
+                }
+                _ => writeln!(ui, "{value}")?,
+            };
+        }
+        ConfigSubcommand::List {} => {
+            let config_table = ui.settings().config().collect()?;
+            write_config_entry(ui, "", config_table.into())?;
+        }
+    }
+
+    Ok(())
+}
+
 fn cmd_checkout(
     ui: &mut Ui,
     command: &CommandHelper,
@@ -4214,6 +4274,7 @@ pub fn run_command(
     match &derived_subcommands {
         Commands::Version(sub_args) => cmd_version(ui, command_helper, sub_args),
         Commands::Init(sub_args) => cmd_init(ui, command_helper, sub_args),
+        Commands::Config(sub_args) => cmd_config(ui, command_helper, sub_args),
         Commands::Checkout(sub_args) => cmd_checkout(ui, command_helper, sub_args),
         Commands::Untrack(sub_args) => cmd_untrack(ui, command_helper, sub_args),
         Commands::Files(sub_args) => cmd_files(ui, command_helper, sub_args),

tests/test_config_command.rs

@@ -0,0 +1,56 @@
+// Copyright 2022 The Jujutsu Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use regex::Regex;
+
+use crate::common::TestEnvironment;
+
+pub mod common;
+
+#[test]
+fn test_config_get() {
+    // TODO: Populate expected config values explicitly in this file.
+    let test_env = TestEnvironment::default();
+    let stdout = test_env.jj_cmd_success(test_env.env_root(), &["config", "get", "user.name"]);
+    insta::assert_snapshot!(stdout, @"Test User");
+}
+
+#[test]
+fn test_config_get_table() {
+    let test_env = TestEnvironment::default();
+    let stdout = test_env.jj_cmd_success(test_env.env_root(), &["config", "get", "user"]);
+    insta::assert_snapshot!(
+        find_stdout_line("user.name", &stdout),
+        @"user.name=Test User");
+    insta::assert_snapshot!(
+        find_stdout_line("user.email", &stdout),
+        @"[email protected]");
+}
+
+#[test]
+fn test_config_list() {
+    let test_env = TestEnvironment::default();
+    let stdout = test_env.jj_cmd_success(test_env.env_root(), &["config", "list"]);
+    insta::assert_snapshot!(
+        find_stdout_line("user.name", &stdout),
+        @"user.name=Test User");
+    insta::assert_snapshot!(
+        find_stdout_line("operation.hostname", &stdout),
+        @"operation.hostname=host.example.com");
+}
+
+fn find_stdout_line<'a>(keyname: &str, stdout: &'a str) -> &'a str {
+    let key_line_re = Regex::new(&format!(r"(?m)^{keyname}=.*$")).unwrap();
+    key_line_re.find(stdout).unwrap().as_str()
+}