diff --git a/tests/common/mod.rs b/tests/common/mod.rs
index d4be8b4..550f3c4 100644
--- a/tests/common/mod.rs
+++ b/tests/common/mod.rs
@@ -1,11 +1,12 @@
 #![allow(dead_code, unreachable_pub)]
 
 use std::env;
+use std::ffi::OsStr;
 use std::path::{Path, PathBuf};
 use std::process::Command;
 
 use assert_cmd::assert::OutputAssertExt;
-use assert_fs::fixture::{ChildPath, PathChild};
+use assert_fs::fixture::{ChildPath, FileWriteStr, PathChild};
 use etcetera::BaseStrategy;
 
 pub struct TestContext {
@@ -227,6 +228,24 @@ impl TestContext {
             .assert()
             .success();
     }
+
+    /// Run `git add` in the temporary directory.
+    pub fn git_add(&self, path: impl AsRef<OsStr>) {
+        Command::new("git")
+            .arg("add")
+            .arg(path)
+            .current_dir(&self.temp_dir)
+            .assert()
+            .success();
+    }
+
+    /// Write a `.pre-commit-config.yaml` file in the temporary directory.
+    pub fn write_pre_commit_config(&self, content: &str) {
+        self.temp_dir
+            .child(".pre-commit-config.yaml")
+            .write_str(content)
+            .expect("Failed to write pre-commit config");
+    }
 }
 
 #[doc(hidden)] // Macro and test context only, don't use directly.
diff --git a/tests/hook_impl.rs b/tests/hook_impl.rs
index ef5b924..55783be 100644
--- a/tests/hook_impl.rs
+++ b/tests/hook_impl.rs
@@ -1,24 +1,19 @@
-use anyhow::Result;
-use assert_cmd::assert::OutputAssertExt;
-use assert_fs::fixture::{FileWriteStr, PathChild};
+use std::process::Command;
+
 use common::TestContext;
 use indoc::indoc;
-use std::process::Command;
 
 use crate::common::cmd_snapshot;
 
 mod common;
 
 #[test]
-fn hook_impl() -> Result<()> {
+fn hook_impl() {
     let context = TestContext::new();
 
     context.init_project();
 
-    context
-        .workdir()
-        .child(".pre-commit-config.yaml")
-        .write_str(indoc! { r"
+    context.write_pre_commit_config(indoc! { r"
             repos:
             - repo: local
               hooks:
@@ -28,14 +23,9 @@ fn hook_impl() -> Result<()> {
                  entry: always fail
                  always_run: true
             "
-        })?;
+    });
 
-    Command::new("git")
-        .arg("add")
-        .current_dir(context.workdir())
-        .arg(".")
-        .assert()
-        .success();
+    context.git_add(".");
 
     let mut commit = Command::new("git");
     commit
@@ -66,6 +56,4 @@ fn hook_impl() -> Result<()> {
 
       .pre-commit-config.yaml
     "#);
-
-    Ok(())
 }
diff --git a/tests/language.rs b/tests/language.rs
index dadbc3e..843d2eb 100644
--- a/tests/language.rs
+++ b/tests/language.rs
@@ -1,8 +1,8 @@
-use crate::common::{cmd_snapshot, TestContext};
 use anyhow::Result;
-use assert_cmd::Command;
 use assert_fs::prelude::*;
 
+use crate::common::{cmd_snapshot, TestContext};
+
 mod common;
 
 #[test]
@@ -15,8 +15,7 @@ fn fail() -> Result<()> {
     cwd.child("changelog").create_dir_all()?;
     cwd.child("changelog/changelog.md").touch()?;
 
-    cwd.child(".pre-commit-config.yaml")
-        .write_str(indoc::indoc! {r"
+    context.write_pre_commit_config(indoc::indoc! {r"
             repos:
               - repo: local
                 hooks:
@@ -25,14 +24,9 @@ fn fail() -> Result<()> {
                   entry: changelog filenames must end in .rst
                   language: fail
                   files: 'changelog/.*(?<!\.rst)$'
-        "})?;
-
-    Command::new("git")
-        .current_dir(cwd)
-        .arg("add")
-        .arg(".")
-        .assert()
-        .success();
+        "});
+
+    context.git_add(".");
 
     cmd_snapshot!(context.filters(), context.run(), @r#"
     success: false
diff --git a/tests/run.rs b/tests/run.rs
index c3d4809..00b9a79 100644
--- a/tests/run.rs
+++ b/tests/run.rs
@@ -1,18 +1,18 @@
-use crate::common::{cmd_snapshot, TestContext};
 use anyhow::Result;
-use assert_cmd::Command;
 use assert_fs::prelude::*;
 use insta::assert_snapshot;
 
+use crate::common::{cmd_snapshot, TestContext};
+
 mod common;
 
 #[test]
 fn run_basic() -> Result<()> {
     let context = TestContext::new();
+    context.init_project();
 
     let cwd = context.workdir();
-    cwd.child(".pre-commit-config.yaml")
-        .write_str(indoc::indoc! {r"
+    context.write_pre_commit_config(indoc::indoc! {r"
             repos:
               - repo: https://github.com/pre-commit/pre-commit-hooks
                 rev: v5.0.0
@@ -20,24 +20,15 @@ fn run_basic() -> Result<()> {
                   - id: trailing-whitespace
                   - id: end-of-file-fixer
                   - id: check-json
-        "})?;
+        "});
 
     // Create a repository with some files.
     cwd.child("file.txt").write_str("Hello, world!\n")?;
     cwd.child("valid.json").write_str("{}")?;
     cwd.child("invalid.json").write_str("{}")?;
     cwd.child("main.py").write_str(r#"print "abc"  "#)?;
-    Command::new("git")
-        .current_dir(cwd)
-        .arg("init")
-        .assert()
-        .success();
-    Command::new("git")
-        .current_dir(cwd)
-        .arg("add")
-        .arg(".")
-        .assert()
-        .success();
+
+    context.git_add(".");
 
     cmd_snapshot!(context.filters(), context.run(), @r#"
     success: false
@@ -84,22 +75,21 @@ fn run_basic() -> Result<()> {
 }
 
 #[test]
-fn invalid_hook_id() -> Result<()> {
+fn invalid_hook_id() {
     let context = TestContext::new();
 
     context.init_project();
 
-    context
-        .workdir()
-        .child(".pre-commit-config.yaml")
-        .write_str(indoc::indoc! {r"
+    context.write_pre_commit_config(indoc::indoc! {r"
             repos:
               - repo: https://github.com/pre-commit/pre-commit-hooks
                 rev: v5.0.0
                 hooks:
                   - id: trailing-whitespace
             "
-        })?;
+    });
+
+    context.git_add(".");
 
     cmd_snapshot!(context.filters(), context.run().arg("invalid-hook-id"), @r#"
     success: false
@@ -110,8 +100,6 @@ fn invalid_hook_id() -> Result<()> {
     ----- stderr -----
     No hook found for id `invalid-hook-id`
     "#);
-
-    Ok(())
 }
 
 /// `.pre-commit-config.yaml` is not staged.
@@ -123,24 +111,16 @@ fn config_not_staged() -> Result<()> {
 
     context.workdir().child(".pre-commit-config.yaml").touch()?;
 
-    Command::new("git")
-        .arg("add")
-        .arg(".")
-        .current_dir(context.workdir())
-        .assert()
-        .success();
-
-    context
-        .workdir()
-        .child(".pre-commit-config.yaml")
-        .write_str(indoc::indoc! {r"
+    context.git_add(".");
+
+    context.write_pre_commit_config(indoc::indoc! {r"
             repos:
               - repo: https://github.com/pre-commit/pre-commit-hooks
                 rev: v5.0.0
                 hooks:
                   - id: trailing-whitespace
             "
-        })?;
+    });
 
     cmd_snapshot!(context.filters(), context.run().arg("invalid-hook-id"), @r#"
     success: false
@@ -157,15 +137,12 @@ fn config_not_staged() -> Result<()> {
 
 /// Test the output format for a hook with a CJK name.
 #[test]
-fn cjk_hook_name() -> Result<()> {
+fn cjk_hook_name() {
     let context = TestContext::new();
 
     context.init_project();
 
-    context
-        .workdir()
-        .child(".pre-commit-config.yaml")
-        .write_str(indoc::indoc! {r"
+    context.write_pre_commit_config(indoc::indoc! {r"
             repos:
               - repo: https://github.com/pre-commit/pre-commit-hooks
                 rev: v5.0.0
@@ -175,7 +152,9 @@ fn cjk_hook_name() -> Result<()> {
                   - id: end-of-file-fixer
                   - id: check-json
             "
-        })?;
+    });
+
+    context.git_add(".");
 
     cmd_snapshot!(context.filters(), context.run(), @r#"
     success: true
@@ -183,27 +162,22 @@ fn cjk_hook_name() -> Result<()> {
     ----- stdout -----
     Cloning https://github.com/pre-commit/pre-commit-hooks@v5.0.0
     Installing environment for https://github.com/pre-commit/pre-commit-hooks@v5.0.0
-    去除行尾空格.........................................(no files to check)Skipped
-    fix end of files.....................................(no files to check)Skipped
+    去除行尾空格.............................................................Passed
+    fix end of files.........................................................Passed
     check json...........................................(no files to check)Skipped
 
     ----- stderr -----
     "#);
-
-    Ok(())
 }
 
 /// Skips hooks based on the `SKIP` environment variable.
 #[test]
-fn skips() -> Result<()> {
+fn skips() {
     let context = TestContext::new();
 
     context.init_project();
 
-    context
-        .workdir()
-        .child(".pre-commit-config.yaml")
-        .write_str(indoc::indoc! {r"
+    context.write_pre_commit_config(indoc::indoc! {r"
             repos:
               - repo: https://github.com/pre-commit/pre-commit-hooks
                 rev: v5.0.0
@@ -212,7 +186,9 @@ fn skips() -> Result<()> {
                   - id: end-of-file-fixer
                   - id: check-json
             "
-        })?;
+    });
+
+    context.git_add(".");
 
     cmd_snapshot!(context.filters(), context.run().env("SKIP", "end-of-file-fixer"), @r#"
     success: true
@@ -220,7 +196,7 @@ fn skips() -> Result<()> {
     ----- stdout -----
     Cloning https://github.com/pre-commit/pre-commit-hooks@v5.0.0
     Installing environment for https://github.com/pre-commit/pre-commit-hooks@v5.0.0
-    trim trailing whitespace.............................(no files to check)Skipped
+    trim trailing whitespace.................................................Passed
     fix end of files........................................................Skipped
     check json...........................................(no files to check)Skipped
 
@@ -237,7 +213,6 @@ fn skips() -> Result<()> {
 
     ----- stderr -----
     "#);
-    Ok(())
 }
 
 /// Test global `files`, `exclude`, and hook level `files`, `exclude`.
@@ -254,10 +229,7 @@ fn files_and_exclude() -> Result<()> {
     cwd.child("main.py").write_str(r#"print "abc"  "#)?;
 
     // Global files and exclude.
-    context
-        .workdir()
-        .child(".pre-commit-config.yaml")
-        .write_str(indoc::indoc! {r"
+    context.write_pre_commit_config(indoc::indoc! {r"
             files: file.txt
             repos:
               - repo: https://github.com/pre-commit/pre-commit-hooks
@@ -267,14 +239,9 @@ fn files_and_exclude() -> Result<()> {
                   - id: end-of-file-fixer
                   - id: check-json
             "
-        })?;
+    });
 
-    Command::new("git")
-        .arg("add")
-        .arg(".")
-        .current_dir(cwd)
-        .assert()
-        .success();
+    context.git_add(".");
 
     cmd_snapshot!(context.filters(), context.run(), @r#"
     success: false
@@ -295,10 +262,7 @@ fn files_and_exclude() -> Result<()> {
 
     // Override hook level files and exclude.
     // Global files and exclude.
-    context
-        .workdir()
-        .child(".pre-commit-config.yaml")
-        .write_str(indoc::indoc! {r"
+    context.write_pre_commit_config(indoc::indoc! {r"
             repos:
               - repo: https://github.com/pre-commit/pre-commit-hooks
                 rev: v5.0.0
@@ -309,14 +273,9 @@ fn files_and_exclude() -> Result<()> {
                     exclude: (valid.json|main.py)
                   - id: check-json
             "
-        })?;
+    });
 
-    Command::new("git")
-        .arg("add")
-        .arg(".")
-        .current_dir(cwd)
-        .assert()
-        .success();
+    context.git_add(".");
 
     cmd_snapshot!(context.filters(), context.run(), @r#"
     success: false
@@ -349,10 +308,7 @@ fn file_types() -> Result<()> {
     cwd.child("main.py").write_str(r#"print "abc"  "#)?;
 
     // Global files and exclude.
-    context
-        .workdir()
-        .child(".pre-commit-config.yaml")
-        .write_str(indoc::indoc! {r#"
+    context.write_pre_commit_config(indoc::indoc! {r#"
             repos:
               - repo: https://github.com/pre-commit/pre-commit-hooks
                 rev: v5.0.0
@@ -367,14 +323,9 @@ fn file_types() -> Result<()> {
                     types: [ "json" ]
                     exclude_types: [ "json" ]
             "#
-        })?;
+    });
 
-    Command::new("git")
-        .arg("add")
-        .arg(".")
-        .current_dir(cwd)
-        .assert()
-        .success();
+    context.git_add(".");
 
     cmd_snapshot!(context.filters(), context.run(), @r#"
     success: false
@@ -418,10 +369,7 @@ fn fail_fast() -> Result<()> {
     cwd.child("main.py").write_str(r#"print "abc"  "#)?;
 
     // Global files and exclude.
-    context
-        .workdir()
-        .child(".pre-commit-config.yaml")
-        .write_str(indoc::indoc! {r#"
+    context.write_pre_commit_config(indoc::indoc! {r#"
             repos:
               - repo: https://github.com/pre-commit/pre-commit-hooks
                 rev: v5.0.0
@@ -434,14 +382,9 @@ fn fail_fast() -> Result<()> {
                   - id: trailing-whitespace
                   - id: trailing-whitespace
             "#
-        })?;
+    });
 
-    Command::new("git")
-        .arg("add")
-        .arg(".")
-        .current_dir(cwd)
-        .assert()
-        .success();
+    context.git_add(".");
 
     cmd_snapshot!(context.filters(), context.run(), @r#"
     success: false
@@ -480,24 +423,16 @@ fn subdirectory() -> Result<()> {
     child.child("file.txt").write_str("Hello, world!  ")?;
 
     // Global files and exclude.
-    context
-        .workdir()
-        .child(".pre-commit-config.yaml")
-        .write_str(indoc::indoc! {r"
+    context.write_pre_commit_config(indoc::indoc! {r"
             repos:
               - repo: https://github.com/pre-commit/pre-commit-hooks
                 rev: v5.0.0
                 hooks:
                   - id: trailing-whitespace
             "
-        })?;
+    });
 
-    Command::new("git")
-        .arg("add")
-        .arg(".")
-        .current_dir(cwd)
-        .assert()
-        .success();
+    context.git_add(".");
 
     cmd_snapshot!(context.filters(), context.run().current_dir(&child).arg("--files").arg("file.txt"), @r#"
     success: false
@@ -528,10 +463,7 @@ fn log_file() -> Result<()> {
     cwd.child("file.txt").write_str("Hello, world!  ")?;
 
     // Global files and exclude.
-    context
-        .workdir()
-        .child(".pre-commit-config.yaml")
-        .write_str(indoc::indoc! {r"
+    context.write_pre_commit_config(indoc::indoc! {r"
             repos:
               - repo: https://github.com/pre-commit/pre-commit-hooks
                 rev: v5.0.0
@@ -539,14 +471,9 @@ fn log_file() -> Result<()> {
                   - id: trailing-whitespace
                     log_file: log.txt
             "
-        })?;
+    });
 
-    Command::new("git")
-        .arg("add")
-        .arg(".")
-        .current_dir(cwd)
-        .assert()
-        .success();
+    context.git_add(".");
 
     cmd_snapshot!(context.filters(), context.run(), @r#"
     success: false
@@ -571,15 +498,12 @@ fn log_file() -> Result<()> {
 /// Pass pre-commit environment variables to the hook.
 #[cfg(unix)]
 #[test]
-fn pass_env_vars() -> Result<()> {
+fn pass_env_vars() {
     let context = TestContext::new();
 
     context.init_project();
 
-    context
-        .workdir()
-        .child(".pre-commit-config.yaml")
-        .write_str(indoc::indoc! {r#"
+    context.write_pre_commit_config(indoc::indoc! {r#"
             repos:
               - repo: local
                 hooks:
@@ -588,7 +512,7 @@ fn pass_env_vars() -> Result<()> {
                     language: system
                     entry: sh -c "echo $PRE_COMMIT > env.txt"
                     always_run: true
-        "#})?;
+        "#});
 
     cmd_snapshot!(context.filters(), context.run(), @r#"
     success: true
@@ -601,6 +525,4 @@ fn pass_env_vars() -> Result<()> {
 
     let env = context.read("env.txt");
     assert_eq!(env, "1\n");
-
-    Ok(())
 }
diff --git a/tests/validate.rs b/tests/validate.rs
index f9ccf8b..c75e989 100644
--- a/tests/validate.rs
+++ b/tests/validate.rs
@@ -17,10 +17,7 @@ fn validate_config() -> anyhow::Result<()> {
     ----- stderr -----
     "#);
 
-    context
-        .workdir()
-        .child(".pre-commit-config.yaml")
-        .write_str(indoc::indoc! {r"
+    context.write_pre_commit_config(indoc::indoc! {r"
             repos:
               - repo: https://github.com/pre-commit/pre-commit-hooks
                 rev: v5.0.0
@@ -28,7 +25,7 @@ fn validate_config() -> anyhow::Result<()> {
                   - id: trailing-whitespace
                   - id: end-of-file-fixer
                   - id: check-json
-        "})?;
+        "});
     // Validate one file.
     cmd_snapshot!(context.filters(), context.validate_config().arg(".pre-commit-config.yaml"), @r#"
     success: true