[skip ci] add checkPackageInstalled and refactor FirefoxKtTest.kt

src/main/kotlin/org/domaindrivenarchitecture/provs/framework/ubuntu/install/base/Install.kt

@@ -72,6 +72,14 @@ fun Prov.isPackageInstalled(packageName: String): Boolean {
 }
 
 
+/**
+ * Returns true if a package is installed else false
+ */
+fun Prov.checkPackageInstalled(packageName: String): ProvResult = taskWithResult {
+    cmd("dpkg -s $packageName")
+}
+
+
 /**
  * Removes a package including its configuration and data file
  */

src/test/kotlin/org/domaindrivenarchitecture/provs/desktop/infrastructure/FirefoxKtTest.kt

@@ -1,6 +1,6 @@
 package org.domaindrivenarchitecture.provs.desktop.infrastructure
 
-import org.domaindrivenarchitecture.provs.framework.ubuntu.install.base.isPackageInstalled
+import org.domaindrivenarchitecture.provs.framework.ubuntu.install.base.checkPackageInstalled
 import org.domaindrivenarchitecture.provs.test.defaultTestContainer
 import org.domaindrivenarchitecture.provs.test.tags.ExtensiveContainerTest
 import org.junit.jupiter.api.Assertions.assertTrue
@@ -9,15 +9,13 @@ internal class FirefoxKtTest {
 
     @ExtensiveContainerTest
     fun installFirefox() {
-        defaultTestContainer().session {
         // when
-            val res = installFirefox()
+        val result = defaultTestContainer().session {
+            installFirefox()
+            checkPackageInstalled("firefox")
+        }
 
         // then
-            assertTrue(res.success)
+        assertTrue(result.success)
-
-            val ffIsInstalled = isPackageInstalled("firefox")
-            assertTrue(ffIsInstalled)
-        }
     }
 }