diff --git a/internal/upstreamldap/upstreamldap.go b/internal/upstreamldap/upstreamldap.go
index eca83707..b5d79c80 100644
--- a/internal/upstreamldap/upstreamldap.go
+++ b/internal/upstreamldap/upstreamldap.go
@@ -188,7 +188,6 @@ func (p *Provider) AuthenticateUser(ctx context.Context, username, password stri
 
 	err = conn.Bind(p.BindUsername, p.BindPassword)
 	if err != nil {
-		// TODO test this
 		return nil, false, fmt.Errorf(`error binding as "%s" before user search: %w`, p.BindUsername, err)
 	}
 
@@ -210,37 +209,31 @@ func (p *Provider) AuthenticateUser(ctx context.Context, username, password stri
 func (p *Provider) searchAndBindUser(conn Conn, username string, password string) (string, string, error) {
 	searchResult, err := conn.Search(p.userSearchRequest(username))
 	if err != nil {
-		// TODO test this
 		return "", "", fmt.Errorf(`error searching for user "%s": %w`, username, err)
 	}
 	if len(searchResult.Entries) != 1 {
-		// TODO test this
 		return "", "", fmt.Errorf(`searching for user "%s" resulted in %d search results, but expected 1 result`,
 			username, len(searchResult.Entries),
 		)
 	}
 	userEntry := searchResult.Entries[0]
 	if len(userEntry.DN) == 0 {
-		// TODO test this
 		return "", "", fmt.Errorf(`searching for user "%s" resulted in search result without DN`, username)
 	}
 
 	mappedUsername, err := p.getSearchResultAttributeValue(p.UserSearch.UsernameAttribute, userEntry, username)
 	if err != nil {
-		// TODO test this
 		return "", "", err
 	}
 
 	mappedUID, err := p.getSearchResultAttributeValue(p.UserSearch.UIDAttribute, userEntry, username)
 	if err != nil {
-		// TODO test this
 		return "", "", err
 	}
 
 	// Take care that any other LDAP commands after this bind will be run as this user instead of as the configured BindUsername!
 	err = conn.Bind(userEntry.DN, password)
 	if err != nil {
-		// TODO test this
 		return "", "", fmt.Errorf(`error binding for user "%s" using provided password against DN "%s": %w`, username, userEntry.DN, err)
 	}
 
@@ -294,7 +287,6 @@ func (p *Provider) getSearchResultAttributeValue(attributeName string, fromUserE
 	attributeValues := fromUserEntry.GetAttributeValues(attributeName)
 
 	if len(attributeValues) != 1 {
-		// TODO test this
 		return "", fmt.Errorf(`found %d values for attribute "%s" while searching for user "%s", but expected 1 result`,
 			len(attributeValues), attributeName, username,
 		)
@@ -302,7 +294,6 @@ func (p *Provider) getSearchResultAttributeValue(attributeName string, fromUserE
 
 	attributeValue := attributeValues[0]
 	if len(attributeValue) == 0 {
-		// TODO test this
 		return "", fmt.Errorf(`found empty value for attribute "%s" while searching for user "%s", but expected value to be non-empty`,
 			attributeName, username,
 		)
diff --git a/internal/upstreamldap/upstreamldap_test.go b/internal/upstreamldap/upstreamldap_test.go
index 9b17c537..61b2a305 100644
--- a/internal/upstreamldap/upstreamldap_test.go
+++ b/internal/upstreamldap/upstreamldap_test.go
@@ -255,6 +255,233 @@ func TestAuthenticateUser(t *testing.T) {
 			dialError: errors.New("some dial error"),
 			wantError: fmt.Sprintf(`error dialing host "%s": some dial error`, testHost),
 		},
+		{
+			name:     "when binding as the bind user returns an error",
+			provider: provider(nil),
+			setupMocks: func(conn *mockldapconn.MockConn) {
+				conn.EXPECT().Bind(testBindUsername, testBindPassword).Return(errors.New("some bind error")).Times(1)
+				conn.EXPECT().Close().Times(1)
+			},
+			wantError: fmt.Sprintf(`error binding as "%s" before user search: some bind error`, testBindUsername),
+		},
+		{
+			name:     "when searching for the user returns an error",
+			username: testUpstreamUsername,
+			password: testUpstreamPassword,
+			provider: provider(nil),
+			setupMocks: func(conn *mockldapconn.MockConn) {
+				conn.EXPECT().Bind(testBindUsername, testBindPassword).Times(1)
+				conn.EXPECT().Search(expectedSearch(nil)).Return(nil, errors.New("some search error")).Times(1)
+				conn.EXPECT().Close().Times(1)
+			},
+			wantError: fmt.Sprintf(`error searching for user "%s": some search error`, testUpstreamUsername),
+		},
+		{
+			name:     "when searching for the user returns no results",
+			username: testUpstreamUsername,
+			password: testUpstreamPassword,
+			provider: provider(nil),
+			setupMocks: func(conn *mockldapconn.MockConn) {
+				conn.EXPECT().Bind(testBindUsername, testBindPassword).Times(1)
+				conn.EXPECT().Search(expectedSearch(nil)).Return(&ldap.SearchResult{
+					Entries: []*ldap.Entry{},
+				}, nil).Times(1)
+				conn.EXPECT().Close().Times(1)
+			},
+			wantError: fmt.Sprintf(`searching for user "%s" resulted in 0 search results, but expected 1 result`, testUpstreamUsername),
+		},
+		{
+			name:     "when searching for the user returns multiple results",
+			username: testUpstreamUsername,
+			password: testUpstreamPassword,
+			provider: provider(nil),
+			setupMocks: func(conn *mockldapconn.MockConn) {
+				conn.EXPECT().Bind(testBindUsername, testBindPassword).Times(1)
+				conn.EXPECT().Search(expectedSearch(nil)).Return(&ldap.SearchResult{
+					Entries: []*ldap.Entry{
+						{DN: testSearchResultDNValue},
+						{DN: "some-other-dn"},
+					},
+				}, nil).Times(1)
+				conn.EXPECT().Close().Times(1)
+			},
+			wantError: fmt.Sprintf(`searching for user "%s" resulted in 2 search results, but expected 1 result`, testUpstreamUsername),
+		},
+		{
+			name:     "when searching for the user returns a user without a DN",
+			username: testUpstreamUsername,
+			password: testUpstreamPassword,
+			provider: provider(nil),
+			setupMocks: func(conn *mockldapconn.MockConn) {
+				conn.EXPECT().Bind(testBindUsername, testBindPassword).Times(1)
+				conn.EXPECT().Search(expectedSearch(nil)).Return(&ldap.SearchResult{
+					Entries: []*ldap.Entry{
+						{DN: ""},
+					},
+				}, nil).Times(1)
+				conn.EXPECT().Close().Times(1)
+			},
+			wantError: fmt.Sprintf(`searching for user "%s" resulted in search result without DN`, testUpstreamUsername),
+		},
+		{
+			name:     "when searching for the user returns a user without an expected username attribute",
+			username: testUpstreamUsername,
+			password: testUpstreamPassword,
+			provider: provider(nil),
+			setupMocks: func(conn *mockldapconn.MockConn) {
+				conn.EXPECT().Bind(testBindUsername, testBindPassword).Times(1)
+				conn.EXPECT().Search(expectedSearch(nil)).Return(&ldap.SearchResult{
+					Entries: []*ldap.Entry{
+						{
+							DN: testSearchResultDNValue,
+							Attributes: []*ldap.EntryAttribute{
+								ldap.NewEntryAttribute(testUserSearchUIDAttribute, []string{testSearchResultUIDAttributeValue}),
+							},
+						},
+					},
+				}, nil).Times(1)
+				conn.EXPECT().Close().Times(1)
+			},
+			wantError: fmt.Sprintf(`found 0 values for attribute "%s" while searching for user "%s", but expected 1 result`, testUserSearchUsernameAttribute, testUpstreamUsername),
+		},
+		{
+			name:     "when searching for the user returns a user with too many values for the expected username attribute",
+			username: testUpstreamUsername,
+			password: testUpstreamPassword,
+			provider: provider(nil),
+			setupMocks: func(conn *mockldapconn.MockConn) {
+				conn.EXPECT().Bind(testBindUsername, testBindPassword).Times(1)
+				conn.EXPECT().Search(expectedSearch(nil)).Return(&ldap.SearchResult{
+					Entries: []*ldap.Entry{
+						{
+							DN: testSearchResultDNValue,
+							Attributes: []*ldap.EntryAttribute{
+								ldap.NewEntryAttribute(testUserSearchUsernameAttribute, []string{
+									testSearchResultUsernameAttributeValue,
+									"unexpected-additional-value",
+								}),
+								ldap.NewEntryAttribute(testUserSearchUIDAttribute, []string{testSearchResultUIDAttributeValue}),
+							},
+						},
+					},
+				}, nil).Times(1)
+				conn.EXPECT().Close().Times(1)
+			},
+			wantError: fmt.Sprintf(`found 2 values for attribute "%s" while searching for user "%s", but expected 1 result`, testUserSearchUsernameAttribute, testUpstreamUsername),
+		},
+		{
+			name:     "when searching for the user returns a user with an empty value for the expected username attribute",
+			username: testUpstreamUsername,
+			password: testUpstreamPassword,
+			provider: provider(nil),
+			setupMocks: func(conn *mockldapconn.MockConn) {
+				conn.EXPECT().Bind(testBindUsername, testBindPassword).Times(1)
+				conn.EXPECT().Search(expectedSearch(nil)).Return(&ldap.SearchResult{
+					Entries: []*ldap.Entry{
+						{
+							DN: testSearchResultDNValue,
+							Attributes: []*ldap.EntryAttribute{
+								ldap.NewEntryAttribute(testUserSearchUsernameAttribute, []string{""}),
+								ldap.NewEntryAttribute(testUserSearchUIDAttribute, []string{testSearchResultUIDAttributeValue}),
+							},
+						},
+					},
+				}, nil).Times(1)
+				conn.EXPECT().Close().Times(1)
+			},
+			wantError: fmt.Sprintf(`found empty value for attribute "%s" while searching for user "%s", but expected value to be non-empty`, testUserSearchUsernameAttribute, testUpstreamUsername),
+		},
+		{
+			name:     "when searching for the user returns a user without an expected UID attribute",
+			username: testUpstreamUsername,
+			password: testUpstreamPassword,
+			provider: provider(nil),
+			setupMocks: func(conn *mockldapconn.MockConn) {
+				conn.EXPECT().Bind(testBindUsername, testBindPassword).Times(1)
+				conn.EXPECT().Search(expectedSearch(nil)).Return(&ldap.SearchResult{
+					Entries: []*ldap.Entry{
+						{
+							DN: testSearchResultDNValue,
+							Attributes: []*ldap.EntryAttribute{
+								ldap.NewEntryAttribute(testUserSearchUsernameAttribute, []string{testSearchResultUsernameAttributeValue}),
+							},
+						},
+					},
+				}, nil).Times(1)
+				conn.EXPECT().Close().Times(1)
+			},
+			wantError: fmt.Sprintf(`found 0 values for attribute "%s" while searching for user "%s", but expected 1 result`, testUserSearchUIDAttribute, testUpstreamUsername),
+		},
+		{
+			name:     "when searching for the user returns a user with too many values for the expected UID attribute",
+			username: testUpstreamUsername,
+			password: testUpstreamPassword,
+			provider: provider(nil),
+			setupMocks: func(conn *mockldapconn.MockConn) {
+				conn.EXPECT().Bind(testBindUsername, testBindPassword).Times(1)
+				conn.EXPECT().Search(expectedSearch(nil)).Return(&ldap.SearchResult{
+					Entries: []*ldap.Entry{
+						{
+							DN: testSearchResultDNValue,
+							Attributes: []*ldap.EntryAttribute{
+								ldap.NewEntryAttribute(testUserSearchUsernameAttribute, []string{testSearchResultUsernameAttributeValue}),
+								ldap.NewEntryAttribute(testUserSearchUIDAttribute, []string{
+									testSearchResultUIDAttributeValue,
+									"unexpected-additional-value",
+								}),
+							},
+						},
+					},
+				}, nil).Times(1)
+				conn.EXPECT().Close().Times(1)
+			},
+			wantError: fmt.Sprintf(`found 2 values for attribute "%s" while searching for user "%s", but expected 1 result`, testUserSearchUIDAttribute, testUpstreamUsername),
+		},
+		{
+			name:     "when searching for the user returns a user with an empty value for the expected UID attribute",
+			username: testUpstreamUsername,
+			password: testUpstreamPassword,
+			provider: provider(nil),
+			setupMocks: func(conn *mockldapconn.MockConn) {
+				conn.EXPECT().Bind(testBindUsername, testBindPassword).Times(1)
+				conn.EXPECT().Search(expectedSearch(nil)).Return(&ldap.SearchResult{
+					Entries: []*ldap.Entry{
+						{
+							DN: testSearchResultDNValue,
+							Attributes: []*ldap.EntryAttribute{
+								ldap.NewEntryAttribute(testUserSearchUsernameAttribute, []string{testSearchResultUsernameAttributeValue}),
+								ldap.NewEntryAttribute(testUserSearchUIDAttribute, []string{""}),
+							},
+						},
+					},
+				}, nil).Times(1)
+				conn.EXPECT().Close().Times(1)
+			},
+			wantError: fmt.Sprintf(`found empty value for attribute "%s" while searching for user "%s", but expected value to be non-empty`, testUserSearchUIDAttribute, testUpstreamUsername),
+		},
+		{
+			name:     "when binding as the found user returns an error",
+			username: testUpstreamUsername,
+			password: testUpstreamPassword,
+			provider: provider(nil),
+			setupMocks: func(conn *mockldapconn.MockConn) {
+				conn.EXPECT().Bind(testBindUsername, testBindPassword).Times(1)
+				conn.EXPECT().Search(expectedSearch(nil)).Return(&ldap.SearchResult{
+					Entries: []*ldap.Entry{
+						{
+							DN: testSearchResultDNValue,
+							Attributes: []*ldap.EntryAttribute{
+								ldap.NewEntryAttribute(testUserSearchUsernameAttribute, []string{testSearchResultUsernameAttributeValue}),
+								ldap.NewEntryAttribute(testUserSearchUIDAttribute, []string{testSearchResultUIDAttributeValue}),
+							},
+						},
+					},
+				}, nil).Times(1)
+				conn.EXPECT().Bind(testSearchResultDNValue, testUpstreamPassword).Return(errors.New("some bind error")).Times(1)
+				conn.EXPECT().Close().Times(1)
+			},
+			wantError: fmt.Sprintf(`error binding for user "%s" using provided password against DN "%s": some bind error`, testUpstreamUsername, testSearchResultDNValue),
+		},
 	}
 
 	for _, test := range tests {