feat: Add --no-warn-conficts flag to suppress warnings on conflicts.

When loading secrets from multiple services, chamber will warn about environment
variables that get overwritten. Use the `--no-warn-conflicts` flag to suppress
these warnings when conflicts are expected:

    chamber exec --no-warn-conflicts defaults/app production/app -- <your executable>

Add tests to verify the storage systems handle invalid AWS_PROFILE variables.
Fix tests which don't handle invalid profiles.

Author: mlanett

README.md

@@ -239,6 +239,14 @@ example, if you do `chamber exec app apptwo -- ...` and both apps have a secret
 named `api_key`, the `api_key` from `apptwo` will be the one set in your
 environment.
 
+When loading secrets from multiple services, chamber will warn about environment
+variables that get overwritten. Use the `--no-warn-conflicts` flag to suppress
+these warnings when conflicts are expected:
+
+```bash
+$ chamber exec --no-warn-conflicts app apptwo -- <your executable>
+```
+
 ### Reading
 
 ```bash

cmd/exec.go

@@ -24,6 +24,9 @@ var strictValue string
 // Default value to expect in strict mode
 const strictValueDefault = "chamberme"
 
+// When true, suppress warnings about conflicting environment variables
+var noWarnConflicts bool
+
 // execCmd represents the exec command
 var execCmd = &cobra.Command{
 	Use:   "exec <service...> -- <command> [<arg...>]",
@@ -58,6 +61,11 @@ Given a secret store like this:
 	$ HOME=/tmp DB_USERNAME=chamberme DB_PASSWORD=chamberme chamber exec --strict --pristine service exec -- env
 	DB_USERNAME=root
 	DB_PASSWORD=hunter22
+
+--no-warn-conflicts suppresses warnings when services overwrite environment variables
+
+	$ chamber exec --no-warn-conflicts service1 service2 -- env
+	# No warnings about conflicting keys between service1 and service2
 `,
 }
 
@@ -68,6 +76,7 @@ only inject secrets for which there is a corresponding env var with value
 <strict-value>, and fail if there are any env vars with that value missing
 from secrets`)
 	execCmd.Flags().StringVar(&strictValue, "strict-value", strictValueDefault, "value to expect in --strict mode")
+	execCmd.Flags().BoolVar(&noWarnConflicts, "no-warn-conflicts", false, "suppress warnings when services overwrite environment variables (useful when conflicts are expected)")
 	RootCmd.AddCommand(execCmd)
 }
 
@@ -123,8 +132,10 @@ func execRun(cmd *cobra.Command, args []string) error {
 				return fmt.Errorf("Failed to list store contents: %w", err)
 			}
 
-			for _, c := range collisions {
-				fmt.Fprintf(os.Stderr, "warning: service %s overwriting environment variable %s\n", service, c)
+			if !noWarnConflicts {
+				for _, c := range collisions {
+					fmt.Fprintf(os.Stderr, "warning: service %s overwriting environment variable %s\n", service, c)
+				}
 			}
 		}
 	}

cmd/exec_test.go

@@ -0,0 +1,113 @@
+package cmd
+
+import (
+	"bytes"
+	"os"
+	"testing"
+
+	"github.com/spf13/cobra"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestExecCommandFlags(t *testing.T) {
+	t.Run("no-warn-conflicts flag should be defined", func(t *testing.T) {
+		// Reset the flag to default state
+		noWarnConflicts = false
+		
+		// Create a new exec command to test flag parsing
+		cmd := &cobra.Command{}
+		cmd.Flags().BoolVar(&noWarnConflicts, "no-warn-conflicts", false, "suppress warnings when services overwrite environment variables")
+		
+		// Test that the flag can be set
+		err := cmd.Flags().Set("no-warn-conflicts", "true")
+		assert.NoError(t, err)
+		assert.True(t, noWarnConflicts)
+		
+		// Test that the flag can be unset
+		err = cmd.Flags().Set("no-warn-conflicts", "false")
+		assert.NoError(t, err)
+		assert.False(t, noWarnConflicts)
+	})
+	
+	t.Run("no-warn-conflicts flag should have correct default value", func(t *testing.T) {
+		// Reset to default state
+		noWarnConflicts = false
+		assert.False(t, noWarnConflicts)
+	})
+}
+
+func TestWarningBehavior(t *testing.T) {
+	// Helper function to capture stderr output
+	captureStderr := func(fn func()) string {
+		oldStderr := os.Stderr
+		r, w, _ := os.Pipe()
+		os.Stderr = w
+		
+		fn()
+		
+		w.Close()
+		os.Stderr = oldStderr
+		
+		var buf bytes.Buffer
+		buf.ReadFrom(r)
+		return buf.String()
+	}
+
+	t.Run("should emit warnings when noWarnConflicts is false", func(t *testing.T) {
+		// Reset to default state
+		noWarnConflicts = false
+		
+		// Simulate the warning logic from exec.go
+		collisions := []string{"DB_HOST", "API_KEY"}
+		service := "test-service"
+		
+		output := captureStderr(func() {
+			if !noWarnConflicts {
+				for _, c := range collisions {
+					os.Stderr.WriteString("warning: service " + service + " overwriting environment variable " + c + "\n")
+				}
+			}
+		})
+		
+		assert.Contains(t, output, "warning: service test-service overwriting environment variable DB_HOST")
+		assert.Contains(t, output, "warning: service test-service overwriting environment variable API_KEY")
+	})
+
+	t.Run("should not emit warnings when noWarnConflicts is true", func(t *testing.T) {
+		// Set flag to suppress warnings
+		noWarnConflicts = true
+		
+		// Simulate the warning logic from exec.go
+		collisions := []string{"DB_HOST", "API_KEY"}
+		service := "test-service"
+		
+		output := captureStderr(func() {
+			if !noWarnConflicts {
+				for _, c := range collisions {
+					os.Stderr.WriteString("warning: service " + service + " overwriting environment variable " + c + "\n")
+				}
+			}
+		})
+		
+		assert.Empty(t, output)
+	})
+
+	t.Run("should handle empty collisions list", func(t *testing.T) {
+		// Reset to default state
+		noWarnConflicts = false
+		
+		// Simulate the warning logic with no collisions
+		collisions := []string{}
+		service := "test-service"
+		
+		output := captureStderr(func() {
+			if !noWarnConflicts {
+				for _, c := range collisions {
+					os.Stderr.WriteString("warning: service " + service + " overwriting environment variable " + c + "\n")
+				}
+			}
+		})
+		
+		assert.Empty(t, output)
+	})
+}

store/secretsmanagerstore_test.go

@@ -222,6 +222,17 @@ func TestNewSecretsManagerStore(t *testing.T) {
 		secretsmanagerClient := s.svc.(*secretsmanager.Client)
 		assert.Nil(t, secretsmanagerClient.Options().BaseEndpoint)
 	})
+
+	t.Run("Should return error when AWS_PROFILE points to invalid profile", func(t *testing.T) {
+		os.Setenv("AWS_PROFILE", "invalid-profile")
+		defer os.Unsetenv("AWS_PROFILE")
+
+		s, err := NewSecretsManagerStore(context.Background(), 1)
+		assert.NotNil(t, err)
+		assert.Nil(t, s)
+		// Verify it's a profile not exist error
+		assert.Contains(t, err.Error(), "profile")
+	})
 }
 
 func TestSecretsManagerWrite(t *testing.T) {

store/ssmstore_test.go

@@ -395,6 +395,17 @@ func TestNewSSMStore(t *testing.T) {
 		assert.Nil(t, err)
 		assert.Equal(t, DefaultRetryMode, s.config.RetryMode)
 	})
+
+	t.Run("Should return error when AWS_PROFILE points to invalid profile", func(t *testing.T) {
+		os.Setenv("AWS_PROFILE", "invalid-profile")
+		defer os.Unsetenv("AWS_PROFILE")
+
+		s, err := NewSSMStore(context.Background(), 1)
+		assert.NotNil(t, err)
+		assert.Nil(t, s)
+		// Verify it's a profile not exist error
+		assert.Contains(t, err.Error(), "profile")
+	})
 }
 
 func TestNewSSMStoreWithRetryMode(t *testing.T) {