diff --git a/client/auth_test.go b/client/auth_test.go
index 9e935f8..8b8f36d 100644
--- a/client/auth_test.go
+++ b/client/auth_test.go
@@ -9,43 +9,84 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func TestClientAuthenticates(t *testing.T) {
-	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
-		var body map[string]interface{}
-		err := readRequestBodyAsJSON(req, &body)
+func Test_portainerClientImp_AuthenticateUser(t *testing.T) {
+	type fields struct {
+		server *httptest.Server
+	}
+	type args struct {
+		options AuthenticateUserOptions
+	}
+	tests := []struct {
+		name      string
+		fields    fields
+		args      args
+		wantToken string
+		wantErr   bool
+	}{
+		{
+			name: "valid username and password authenticates (happy path)",
+			fields: fields{
+				server: httptest.NewUnstartedServer(http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+					assert.Equal(t, req.Method, http.MethodPost)
+					assert.Equal(t, req.RequestURI, "/api/auth")
 
-		assert.Equal(t, req.Method, http.MethodPost)
-		assert.Equal(t, req.RequestURI, "/api/auth")
-		assert.NotNil(t, req.Header["Content-Type"])
-		assert.NotNil(t, req.Header["Content-Type"][0])
-		assert.Equal(t, req.Header["Content-Type"][0], "application/json")
-		assert.NotNil(t, req.Header["User-Agent"])
-		assert.NotNil(t, req.Header["User-Agent"][0])
-		assert.Equal(t, req.Header["User-Agent"][0], "GE007")
-		assert.Nil(t, err)
-		assert.NotNil(t, body["Username"])
-		assert.Equal(t, body["Username"], "admin")
-		assert.NotNil(t, body["Password"])
-		assert.Equal(t, body["Password"], "a")
+					var body map[string]interface{}
+					err := readRequestBodyAsJSON(req, &body)
+					assert.Nil(t, err)
 
-		writeResponseBodyAsJSON(w, map[string]interface{}{
-			"jwt": "somerandomtoken",
+					assert.NotNil(t, body["Username"])
+					assert.Equal(t, body["Username"], "admin")
+					assert.NotNil(t, body["Password"])
+					assert.Equal(t, body["Password"], "a")
+
+					writeResponseBodyAsJSON(w, map[string]interface{}{
+						"jwt": "token",
+					})
+				})),
+			},
+			args: args{
+				options: AuthenticateUserOptions{
+					Username: "admin",
+					Password: "a",
+				},
+			},
+			wantToken: "token",
+		},
+		{
+			name: "invalid username and password does not authenticate",
+			fields: fields{
+				server: httptest.NewUnstartedServer(http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+					w.WriteHeader(http.StatusUnprocessableEntity)
+					writeResponseBodyAsJSON(w, map[string]interface{}{
+						"Err":     "Invalid credentials",
+						"Details": "Unauthorized",
+					})
+				})),
+			},
+			args: args{
+				options: AuthenticateUserOptions{
+					Username: "admin",
+					Password: "a",
+				},
+			},
+			wantErr: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			tt.fields.server.Start()
+			defer tt.fields.server.Close()
+
+			apiURL, _ := url.Parse(tt.fields.server.URL + "/api/")
+
+			n := &portainerClientImp{
+				httpClient: tt.fields.server.Client(),
+				url:        apiURL,
+			}
+
+			gotToken, err := n.AuthenticateUser(tt.args.options)
+			assert.Equal(t, tt.wantErr, err != nil)
+			assert.Equal(t, tt.wantToken, gotToken)
 		})
-	}))
-	defer ts.Close()
-
-	apiURL, _ := url.Parse(ts.URL + "/api/")
-
-	customClient := NewClient(ts.Client(), Config{
-		URL:       apiURL,
-		User:      "admin",
-		Password:  "a",
-		UserAgent: "GE007",
-	})
-	token, err := customClient.AuthenticateUser(AuthenticateUserOptions{
-		Username: "admin",
-		Password: "a",
-	})
-	assert.Nil(t, err)
-	assert.Equal(t, token, "somerandomtoken")
+	}
 }