From 377cc7f377c09f82dabbfda58e8f1630ea9a1a45 Mon Sep 17 00:00:00 2001
From: Matthew Rothenberg <mrothenberg@gmail.com>
Date: Mon, 17 Jan 2022 15:46:07 -0500
Subject: [PATCH] init: auto default shell detection based on $SHELL

---
 commands/inits/init.go      |  9 +++++++++
 commands/inits/init_test.go | 27 +++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)
 create mode 100644 commands/inits/init_test.go

diff --git a/commands/inits/init.go b/commands/inits/init.go
index e8360df..5aaca0f 100644
--- a/commands/inits/init.go
+++ b/commands/inits/init.go
@@ -3,6 +3,7 @@ package inits
 import (
 	"fmt"
 	"os"
+	"path/filepath"
 	"strings"
 
 	"github.com/spf13/cobra"
@@ -97,5 +98,13 @@ There are a number of flags to customize the shell integration.
 // defaultShell returns the shellType assumed if user does not specify.
 // in the future, we may wish to customize this based on the $SHELL variable.
 func defaultShellType() string {
+	if shellenv, ok := os.LookupEnv("SHELL"); ok {
+		base := filepath.Base(shellenv)
+		switch base {
+		case "sh", "bash", "zsh", "fish":
+			return base
+		}
+	}
+
 	return "sh"
 }
diff --git a/commands/inits/init_test.go b/commands/inits/init_test.go
new file mode 100644
index 0000000..029db41
--- /dev/null
+++ b/commands/inits/init_test.go
@@ -0,0 +1,27 @@
+package inits
+
+import "testing"
+
+func Test_defaultShellType(t *testing.T) {
+	tests := []struct {
+		shellenv string
+		want     string
+	}{
+		// supported shells at a bunch of different locations
+		{"/bin/zsh", "zsh"},
+		{"/usr/bin/zsh", "zsh"},
+		{"/usr/local/bin/zsh", "zsh"},
+		{"/bin/bash", "bash"},
+		{"/usr/local/bin/fish", "fish"},
+
+		// edge cases
+		{"", "sh"},
+		{"/bin/unsupported", "sh"},
+	}
+	for _, tt := range tests {
+		t.Setenv("SHELL", tt.shellenv)
+		if got := defaultShellType(); got != tt.want {
+			t.Errorf("defaultShellType(%v) = %v, want %v", tt.shellenv, got, tt.want)
+		}
+	}
+}