Detect user based on key, username or id

This allows gitlab-shell to be called with an argument of the format
`key-123` or `username-name`.

When called in this way, `gitlab-shell` will call the GitLab internal
API. If the API responds with user information, it will print a
welcome message including the username.

If the API responds with a successful but empty response, gitlab-shell
will print a welcome message for an anonymous user.

If the API response includes an error message in JSON, this message
will be printed to stderr.

If the API call fails, an error message including the status code will
be printed to stderr.

1 files changed, 130 insertions, 0 deletions

diff --git a/go/internal/command/discover/discover_test.go b/go/internal/command/discover/discover_test.go
new file mode 100644
index 0000000..752e76e
--- /dev/null
+++ b/go/internal/command/discover/discover_test.go
@@ -0,0 +1,130 @@
+package discover
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"gitlab.com/gitlab-org/gitlab-shell/go/internal/command/commandargs"
+	"gitlab.com/gitlab-org/gitlab-shell/go/internal/config"
+	"gitlab.com/gitlab-org/gitlab-shell/go/internal/gitlabnet/testserver"
+)
+
+var (
+	testConfig = &config.Config{GitlabUrl: "http+unix://" + testserver.TestSocket}
+	requests   = []testserver.TestRequestHandler{
+		{
+			Path: "/api/v4/internal/discover",
+			Handler: func(w http.ResponseWriter, r *http.Request) {
+				if r.URL.Query().Get("key_id") == "1" || r.URL.Query().Get("username") == "alex-doe" {
+					body := map[string]interface{}{
+						"id":       2,
+						"username": "alex-doe",
+						"name":     "Alex Doe",
+					}
+					json.NewEncoder(w).Encode(body)
+				} else if r.URL.Query().Get("username") == "broken_message" {
+					body := map[string]string{
+						"message": "Forbidden!",
+					}
+					w.WriteHeader(http.StatusForbidden)
+					json.NewEncoder(w).Encode(body)
+				} else if r.URL.Query().Get("username") == "broken" {
+					w.WriteHeader(http.StatusInternalServerError)
+				} else {
+					fmt.Fprint(w, "null")
+				}
+			},
+		},
+	}
+)
+
+func TestExecute(t *testing.T) {
+	cleanup, err := testserver.StartSocketHttpServer(requests)
+	require.NoError(t, err)
+	defer cleanup()
+
+	testCases := []struct {
+		desc           string
+		arguments      *commandargs.CommandArgs
+		expectedOutput string
+	}{
+		{
+			desc:           "With a known username",
+			arguments:      &commandargs.CommandArgs{GitlabUsername: "alex-doe"},
+			expectedOutput: "Welcome to GitLab, @alex-doe!\n",
+		},
+		{
+			desc:           "With a known key id",
+			arguments:      &commandargs.CommandArgs{GitlabKeyId: "1"},
+			expectedOutput: "Welcome to GitLab, @alex-doe!\n",
+		},
+		{
+			desc:           "With an unknown key",
+			arguments:      &commandargs.CommandArgs{GitlabKeyId: "-1"},
+			expectedOutput: "Welcome to GitLab, Anonymous!\n",
+		},
+		{
+			desc:           "With an unknown username",
+			arguments:      &commandargs.CommandArgs{GitlabUsername: "unknown"},
+			expectedOutput: "Welcome to GitLab, Anonymous!\n",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.desc, func(t *testing.T) {
+			buffer := &bytes.Buffer{}
+			output = buffer
+			cmd := &Command{Config: testConfig, Args: tc.arguments}
+
+			err := cmd.Execute()
+
+			assert.NoError(t, err)
+			assert.Equal(t, tc.expectedOutput, buffer.String())
+		})
+	}
+}
+
+func TestFailingExecute(t *testing.T) {
+	cleanup, err := testserver.StartSocketHttpServer(requests)
+	require.NoError(t, err)
+	defer cleanup()
+
+	testCases := []struct {
+		desc          string
+		arguments     *commandargs.CommandArgs
+		expectedError string
+	}{
+		{
+			desc:          "With missing arguments",
+			arguments:     &commandargs.CommandArgs{},
+			expectedError: "Failed to get username: who='' is invalid",
+		},
+		{
+			desc:          "When the API returns an error",
+			arguments:     &commandargs.CommandArgs{GitlabUsername: "broken_message"},
+			expectedError: "Failed to get username: Forbidden!",
+		},
+		{
+			desc:          "When the API fails",
+			arguments:     &commandargs.CommandArgs{GitlabUsername: "broken"},
+			expectedError: "Failed to get username: Internal API error (500)",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.desc, func(t *testing.T) {
+			cmd := &Command{Config: testConfig, Args: tc.arguments}
+
+			err := cmd.Execute()
+
+			assert.EqualError(t, err, tc.expectedError)
+		})
+	}
+
+}