diff --git a/src/BaselineOfWebDriver/BaselineOfWebDriver.class.st b/src/BaselineOfWebDriver/BaselineOfWebDriver.class.st
index 2bc1605..d491aac 100644
--- a/src/BaselineOfWebDriver/BaselineOfWebDriver.class.st
+++ b/src/BaselineOfWebDriver/BaselineOfWebDriver.class.st
@@ -13,7 +13,8 @@ BaselineOfWebDriver >> baseline: spec [
 			spec 
 				package: 'WebDriver'
 		];
-		baseline: 'NeoJSON' with: [ spec repository: 'github://svenvc/NeoJSON/repository' ]
+		baseline: 'NeoJSON' with: [ spec repository: 'github://svenvc/NeoJSON/repository' ];
+		baseline: 'OSSubprocess' with: [ spec repository: 'github://pharo-contributions/OSSubprocess:master/repository' ]
 ]
 
 { #category : #accessing }
diff --git a/src/WebDriver-Tests/WebDriverTest.class.st b/src/WebDriver-Tests/WebDriverTest.class.st
new file mode 100644
index 0000000..80ab6b2
--- /dev/null
+++ b/src/WebDriver-Tests/WebDriverTest.class.st
@@ -0,0 +1,53 @@
+"
+A WebDriverTest is a test class for testing the behavior of WebDriver
+"
+Class {
+	#name : #WebDriverTest,
+	#superclass : #TestCase,
+	#instVars : [
+		'webdriver'
+	],
+	#category : #'WebDriver-Tests'
+}
+
+{ #category : #initialization }
+WebDriverTest >> setUp [
+	super setUp.
+	webdriver := WebDriver geckodriver.
+	webdriver session.
+]
+
+{ #category : #running }
+WebDriverTest >> tearDown [ 
+	webdriver deleteSession.
+	super tearDown.
+]
+
+{ #category : #tests }
+WebDriverTest >> testFindElementInvalidCSSSelector [
+	self
+		should: [ webdriver url: 'https://ddg.co'; findElement: '' using: WDLocationStrategy cssSelector ]
+		raise: WDInvalidSelector.
+]
+
+{ #category : #tests }
+WebDriverTest >> testFindElementValid [
+	| result |
+	result := webdriver url: 'https://ddg.co'; findElement: '.logo_homepage' using: WDLocationStrategy cssSelector.
+	self assert: (result isString).
+]
+
+{ #category : #tests }
+WebDriverTest >> testFindElementsInvalidCSSSelector [
+	self
+		should: [ webdriver url: 'https://ddg.co'; findElements: '' using: WDLocationStrategy cssSelector ]
+		raise: WDInvalidSelector.
+]
+
+{ #category : #tests }
+WebDriverTest >> testFindElementsValid [
+	| result |
+	result := webdriver url: 'https://ddg.co'; 
+					findElements: '.badge-link__bullet' using: WDLocationStrategy cssSelector.
+	self assert: result size equals: 3.
+]
diff --git a/src/WebDriver-Tests/package.st b/src/WebDriver-Tests/package.st
new file mode 100644
index 0000000..ec0cf5e
--- /dev/null
+++ b/src/WebDriver-Tests/package.st
@@ -0,0 +1 @@
+Package { #name : #'WebDriver-Tests' }
diff --git a/src/WebDriver/WDInvalidSelector.class.st b/src/WebDriver/WDInvalidSelector.class.st
new file mode 100644
index 0000000..b4a762b
--- /dev/null
+++ b/src/WebDriver/WDInvalidSelector.class.st
@@ -0,0 +1,5 @@
+Class {
+	#name : #WDInvalidSelector,
+	#superclass : #Exception,
+	#category : #WebDriver
+}
diff --git a/src/WebDriver/WebDriver.class.st b/src/WebDriver/WebDriver.class.st
index cc2c372..2501731 100644
--- a/src/WebDriver/WebDriver.class.st
+++ b/src/WebDriver/WebDriver.class.st
@@ -11,28 +11,67 @@ Class {
 	#category : #WebDriver
 }
 
-{ #category : #positioning }
+{ #category : #'instance creation' }
+WebDriver class >> geckodriver [
+	| subproc |
+	subproc := OSSUnixSubprocess new
+					command: 'geckodriver'.
+	[ subproc run ] fork.
+   ^	self new 
+		browser: subproc
+		server: '127.0.0.1'
+		port: 4444.
+]
+
+{ #category : #navigation }
 WebDriver >> back [
 	self send: {  } to: 'session/',sessionId,'/back' using: #POST.
 ]
 
-{ #category : #'as yet unclassified' }
+{ #category : #initialization }
+WebDriver >> browser: brs server: srv port: portnum [
+	browser := brs.
+	server := srv.
+	port := portnum.
+]
+
+{ #category : #finalization }
 WebDriver >> deleteSession [
 	"Deletes the session."
 	self send: {} to: 'session/',sessionId using: #DELETE.
 ]
 
-{ #category : #'as yet unclassified' }
+{ #category : #finalization }
+WebDriver >> finalize [ 
+	browser terminate.
+	super finalize.
+]
+
+{ #category : #accessing }
 WebDriver >> findElement: elemSelector using: locStrategy [
-	^(self send: { #using -> locStrategy. #value -> elemSelector. } to: 'session/',sessionId,'/element' using: #POST) at: #value values first.
+	| reply |
+	reply := (self send: { #using -> locStrategy. #value -> elemSelector. } 
+					to: 'session/',sessionId,'/element' 
+					using: #POST) 
+				at: #value.
+	(reply at: #error ifPresent: [ true ] ifAbsent: [ false ])
+		ifTrue: [ ^ WDInvalidSelector new signal: (reply at: #message) ]
+		ifFalse: [ ^ reply values first ]
 ]
 
-{ #category : #'as yet unclassified' }
+{ #category : #accessing }
 WebDriver >> findElements: elemSelector using: locStrategy [
-	^(self send: { #using -> locStrategy. #value -> elemSelector. } to: 'session/',sessionId,'/elements' using: #POST) at: #value values.
+	| reply |
+	reply := (self send: { #using -> locStrategy. #value -> elemSelector. }
+						to: 'session/',sessionId,'/elements'
+						using: #POST)
+				at: #value.
+	(reply isArray)
+		ifTrue: [ ^ reply collect: [ :elem | elem values first ] ]
+		ifFalse: [ ^ WDInvalidSelector new signal: (reply at: #message) ]
 ]
 
-{ #category : #positioning }
+{ #category : #navigation }
 WebDriver >> forward [
 	self send: {  } to: 'session/',sessionId,'/forward' using: #POST.
 ]
@@ -43,12 +82,12 @@ WebDriver >> initialize: srv port: portnum [
 	port := portnum.
 ]
 
-{ #category : #positioning }
+{ #category : #navigation }
 WebDriver >> refresh [
 	self send: {  } to: 'session/',sessionId,'/refresh' using: #POST.
 ]
 
-{ #category : #'as yet unclassified' }
+{ #category : #navigation }
 WebDriver >> send: dict to: url using: method [
 	|result|
 	result := nil.
@@ -66,12 +105,6 @@ WebDriver >> send: dict to: url using: method [
 	^result.
 ]
 
-{ #category : #initialization }
-WebDriver >> server: srv port: portnum [
-	server := srv.
-	port := portnum.
-]
-
 { #category : #accessing }
 WebDriver >> session [
 	"Initializes a new WebDriver session."
@@ -84,18 +117,18 @@ WebDriver >> status [
 	^ (self send: {  } to: 'status' using: #GET) at: #value.
 ]
 
-{ #category : #positioning }
+{ #category : #accessing }
 WebDriver >> title [
 	^ (self send: {  } to: 'session/',sessionId,'/title' using: #GET) at: #value.
 ]
 
-{ #category : #'as yet unclassified' }
+{ #category : #'text input' }
 WebDriver >> type: text into: element [
 	self send: { #text -> text } to: 'session/',sessionId,'/element/',element,'/value' using: #POST.
 	
 ]
 
-{ #category : #accessing }
+{ #category : #navigation }
 WebDriver >> url: url [
 	"Navigates the browser to the given URL."
 	self send: { #url -> url } to: 'session/',sessionId,'/url' using: #POST.