diff --git a/tests/test_squash_command.rs b/tests/test_squash_command.rs
new file mode 100644
index 000000000..e980ef091
--- /dev/null
+++ b/tests/test_squash_command.rs
@@ -0,0 +1,122 @@
+// Copyright 2022 Google LLC
+//
+// 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 crate::common::TestEnvironment;
+
+pub mod common;
+
+#[test]
+fn test_squash() {
+    let test_env = TestEnvironment::default();
+    test_env.jj_cmd_success(test_env.env_root(), &["init", "repo", "--git"]);
+    let repo_path = test_env.env_root().join("repo");
+
+    test_env.jj_cmd_success(&repo_path, &["branch", "a"]);
+    std::fs::write(repo_path.join("file1"), "a\n").unwrap();
+    test_env.jj_cmd_success(&repo_path, &["new"]);
+    test_env.jj_cmd_success(&repo_path, &["branch", "b"]);
+    std::fs::write(repo_path.join("file1"), "b\n").unwrap();
+    test_env.jj_cmd_success(&repo_path, &["new"]);
+    test_env.jj_cmd_success(&repo_path, &["branch", "c"]);
+    std::fs::write(repo_path.join("file1"), "c\n").unwrap();
+    // Test the setup
+    let template = r#"commit_id.short() " " branches"#;
+    let stdout = test_env.jj_cmd_success(&repo_path, &["log", "-T", template]);
+    insta::assert_snapshot!(stdout, @r###"
+    @ 90fe0a96fc90 c
+    o fa5efbdf533c b
+    o 90aeefd03044 a
+    o 000000000000 
+    "###);
+
+    // Squashes the working copy into the parent by default
+    let stdout = test_env.jj_cmd_success(&repo_path, &["squash"]);
+    insta::assert_snapshot!(stdout, @"Working copy now at: 6ca29c9d2e7c 
+");
+    let stdout = test_env.jj_cmd_success(&repo_path, &["log", "-T", template]);
+    insta::assert_snapshot!(stdout, @r###"
+    @ 6ca29c9d2e7c b c
+    o 90aeefd03044 a
+    o 000000000000 
+    "###);
+    let stdout = test_env.jj_cmd_success(&repo_path, &["print", "file1"]);
+    insta::assert_snapshot!(stdout, @"c
+");
+
+    // Can squash a given commit into its parent
+    test_env.jj_cmd_success(&repo_path, &["undo"]);
+    let stdout = test_env.jj_cmd_success(&repo_path, &["squash", "-r", "b"]);
+    insta::assert_snapshot!(stdout, @r###"
+    Rebased 1 descendant commits
+    Working copy now at: e87cf8ebc7e1 
+    "###);
+    let stdout = test_env.jj_cmd_success(&repo_path, &["log", "-T", template]);
+    insta::assert_snapshot!(stdout, @r###"
+    @ e87cf8ebc7e1 c
+    o 893c93ae2a87 a b
+    o 000000000000 
+    "###);
+    let stdout = test_env.jj_cmd_success(&repo_path, &["print", "file1", "-r", "b"]);
+    insta::assert_snapshot!(stdout, @"b
+");
+    let stdout = test_env.jj_cmd_success(&repo_path, &["print", "file1"]);
+    insta::assert_snapshot!(stdout, @"c
+");
+
+    // Cannot squash a merge commit (because it's unclear which parent it should go
+    // into)
+    test_env.jj_cmd_success(&repo_path, &["undo"]);
+    test_env.jj_cmd_success(&repo_path, &["co", "b"]);
+    test_env.jj_cmd_success(&repo_path, &["new"]);
+    test_env.jj_cmd_success(&repo_path, &["branch", "d"]);
+    std::fs::write(repo_path.join("file2"), "d\n").unwrap();
+    test_env.jj_cmd_success(&repo_path, &["merge", "-m", "merge", "c", "d"]);
+    test_env.jj_cmd_success(&repo_path, &["branch", "e", "-r", "@+"]);
+    let stdout = test_env.jj_cmd_success(&repo_path, &["log", "-T", template]);
+    insta::assert_snapshot!(stdout, @r###"
+    o   b9ad3fdfc2c4 e
+    |\  
+    @ | 9a18f8da1e69 d
+    | o 90fe0a96fc90 c
+    |/  
+    o fa5efbdf533c b
+    o 90aeefd03044 a
+    o 000000000000 
+    "###);
+    let stdout = test_env.jj_cmd_failure(&repo_path, &["squash", "-r", "e"]);
+    insta::assert_snapshot!(stdout, @"Error: Cannot squash merge commits
+");
+
+    // Can squash into a merge commit
+    test_env.jj_cmd_success(&repo_path, &["co", "e"]);
+    std::fs::write(repo_path.join("file1"), "e\n").unwrap();
+    let stdout = test_env.jj_cmd_success(&repo_path, &["squash"]);
+    insta::assert_snapshot!(stdout, @"Working copy now at: 626d78245205 
+");
+    let stdout = test_env.jj_cmd_success(&repo_path, &["log", "-T", template]);
+    insta::assert_snapshot!(stdout, @r###"
+    @ 626d78245205 
+    o   2a25465aba5f e
+    |\  
+    o | 9a18f8da1e69 d
+    | o 90fe0a96fc90 c
+    |/  
+    o fa5efbdf533c b
+    o 90aeefd03044 a
+    o 000000000000 
+    "###);
+    let stdout = test_env.jj_cmd_success(&repo_path, &["print", "file1", "-r", "e"]);
+    insta::assert_snapshot!(stdout, @"e
+");
+}