Add CMT_HOME (or remove it?) (celestiaorg#983)

Closes celestiaorg#982

Added `CMT_HOME` everywhere `CMTHOME` is used.

### Notes to reviewers

This could be fixed the opposite way, by removing the only reference to `CMT_HOME` in the code, and also the reference in `UPGRADING.md` (two lines of code).

However, the reference in `UPGRADING.md`, which is part of our documentation, is already present in `v0.34.x` (not in `v0.37.x` though!). That's why this PR introduces `CMT_HOME` to work in equal conditions as `CMTHOME`.

If reviewers lean toward removing `CMT_HOME` from the doc in `v0.34.x` (and unreleased `v0.38.x` and `main`), I can do it easily.


---

#### PR checklist

- [x] Tests written/updated
- [ ] Changelog entry added in `.changelog` (we use [unclog](https://github.com/informalsystems/unclog) to manage our changelog)
- [ ] Updated relevant documentation (`docs/` or `spec/`) and code comments

Author: sergio-mena

UPGRADING.md

@@ -117,7 +117,7 @@ on instead of `~/.tendermint`.
 ### Environment variables
 
 The environment variable prefixes have now changed from `TM` to `CMT`. For
-example, `TMHOME` or `TM_HOME` become `CMTHOME` or `CMT_HOME`.
+example, `TMHOME` becomes `CMTHOME`.
 
 We have implemented a fallback check in case `TMHOME` is still set and `CMTHOME`
 is not, but you will start to see a warning message in the logs if the old

cmd/cometbft/commands/root_test.go

@@ -17,28 +17,12 @@ import (
 	cmtos "github.com/cometbft/cometbft/libs/os"
 )
 
-var defaultRoot = os.ExpandEnv("$HOME/.some/test/dir")
-
 // clearConfig clears env vars, the given root dir, and resets viper.
-func clearConfig(dir string) {
-	if err := os.Unsetenv("CMTHOME"); err != nil {
-		panic(err)
-	}
-	if err := os.Unsetenv("CMT_HOME"); err != nil {
-		panic(err)
-	}
-	if err := os.Unsetenv("TMHOME"); err != nil {
-		// XXX: Deprecated.
-		panic(err)
-	}
-	if err := os.Unsetenv("TM_HOME"); err != nil {
-		// XXX: Deprecated.
-		panic(err)
-	}
+func clearConfig(t *testing.T, dir string) {
+	os.Clearenv()
+	err := os.RemoveAll(dir)
+	require.NoError(t, err)
 
-	if err := os.RemoveAll(dir); err != nil {
-		panic(err)
-	}
 	viper.Reset()
 	config = cfg.DefaultConfig()
 }
@@ -56,34 +40,39 @@ func testRootCmd() *cobra.Command {
 	return rootCmd
 }
 
-func testSetup(args []string, env map[string]string) error {
-	clearConfig(defaultRoot)
+func testSetup(t *testing.T, root string, args []string, env map[string]string) error {
+	clearConfig(t, root)
 
 	rootCmd := testRootCmd()
-	cmd := cli.PrepareBaseCmd(rootCmd, "CMT", defaultRoot)
+	cmd := cli.PrepareBaseCmd(rootCmd, "CMT", root)
 
 	// run with the args and env
 	args = append([]string{rootCmd.Use}, args...)
 	return cli.RunWithArgs(cmd, args, env)
 }
 
 func TestRootHome(t *testing.T) {
-	newRoot := filepath.Join(defaultRoot, "something-else")
+	tmpDir := os.TempDir()
+	root := filepath.Join(tmpDir, "adir")
+	newRoot := filepath.Join(tmpDir, "something-else")
+	defer clearConfig(t, root)
+	defer clearConfig(t, newRoot)
+
 	cases := []struct {
 		args []string
 		env  map[string]string
 		root string
 	}{
-		{nil, nil, defaultRoot},
+		{nil, nil, root},
 		{[]string{"--home", newRoot}, nil, newRoot},
 		{nil, map[string]string{"TMHOME": newRoot}, newRoot}, // XXX: Deprecated.
 		{nil, map[string]string{"CMTHOME": newRoot}, newRoot},
 	}
 
 	for i, tc := range cases {
-		idxString := strconv.Itoa(i)
+		idxString := "idx: " + strconv.Itoa(i)
 
-		err := testSetup(tc.args, tc.env)
+		err := testSetup(t, root, tc.args, tc.env)
 		require.Nil(t, err, idxString)
 
 		assert.Equal(t, tc.root, config.RootDir, idxString)
@@ -115,8 +104,10 @@ func TestRootFlagsEnv(t *testing.T) {
 
 	for i, tc := range cases {
 		idxString := strconv.Itoa(i)
-
-		err := testSetup(tc.args, tc.env)
+		root := filepath.Join(os.TempDir(), "adir2_"+idxString)
+		idxString = "idx: " + idxString
+		defer clearConfig(t, root)
+		err := testSetup(t, root, tc.args, tc.env)
 		require.Nil(t, err, idxString)
 
 		assert.Equal(t, tc.logLevel, config.LogLevel, idxString)
@@ -144,10 +135,11 @@ func TestRootConfig(t *testing.T) {
 
 	for i, tc := range cases {
 		idxString := strconv.Itoa(i)
-		clearConfig(defaultRoot)
-
+		root := filepath.Join(os.TempDir(), "adir3_"+idxString)
+		idxString = "idx: " + idxString
+		defer clearConfig(t, root)
 		// XXX: path must match cfg.defaultConfigPath
-		configFilePath := filepath.Join(defaultRoot, "config")
+		configFilePath := filepath.Join(root, "config")
 		err := cmtos.EnsureDir(configFilePath, 0o700)
 		require.Nil(t, err)
 
@@ -157,7 +149,7 @@ func TestRootConfig(t *testing.T) {
 		require.Nil(t, err)
 
 		rootCmd := testRootCmd()
-		cmd := cli.PrepareBaseCmd(rootCmd, "CMT", defaultRoot)
+		cmd := cli.PrepareBaseCmd(rootCmd, "CMT", root)
 
 		// run with the args and env
 		tc.args = append([]string{rootCmd.Use}, tc.args...)