soft fail when we get api rate limited (#21)

main.go

@@ -24,10 +24,23 @@ var verbose io.Writer = os.Stderr
 func main() {
 	if err := testableMain(os.Stdout, os.Args[1:]); err != nil {
 		fmt.Fprintln(os.Stderr, err)
-		os.Exit(1)
+
+		if isRateLimitErr(err) {
+			fmt.Println("Github API limit reached. Soft exiting")
+		} else {
+			os.Exit(1)
+		}
 	}
 }
 
+func isRateLimitErr(err error) bool {
+	if err == nil {
+		return false
+	}
+
+	return strings.Contains(err.Error(), "API rate limit exceeded")
+}
+
 func testableMain(stdout io.Writer, args []string) error {
 	opts, err := getOptions(stdout, args)
 	if err != nil {

main_test.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"bytes"
+	"fmt"
 	"io/ioutil"
 	"os"
 	"os/exec"
@@ -643,6 +644,33 @@ func TestNotifications(t *testing.T) {
 	}
 }
 
+func TestIsRateLimitErr(t *testing.T) {
+	cases := []struct {
+		err      error
+		expected bool
+	}{
+		{
+			err:      fmt.Errorf("graphql: API rate limit exceeded for user ID 12345"),
+			expected: true,
+		}, {
+			err:      nil,
+			expected: false,
+		}, {
+			err:      fmt.Errorf("fake top error"),
+			expected: false,
+		}, {
+			err:      fmt.Errorf("something something: API rate limit exceeded for user ID 12345"),
+			expected: true,
+		},
+	}
+
+	for _, tc := range cases {
+		if isRateLimitErr(tc.err) != tc.expected {
+			t.Errorf("expected %v got %v for %s", tc.expected, !tc.expected, tc.err)
+		}
+	}
+}
+
 // memfs is an in-memory implementation of the FS interface.
 type memfs map[string]string