Implementation of tests for the interoperability countries selection screen...

Implementation of tests for the interoperability countries selection screen (EXPOSUREAPP-2439) (#1140)

* Added initial set of viewModel tests

Signed-off-by: Kolya Opahle <k.opahle@sap.com>

* Fail tests on unexpected null.

Co-authored-by: Matthias Urhahn <matthias.urhahn@sap.com>

Corona-Warn-App/src/test/java/de/rki/coronawarnapp/ui/submission/viewmodel/SubmissionCountrySelectViewModelTest.kt

+package de.rki.coronawarnapp.ui.submission.viewmodel
+
+import androidx.arch.core.executor.testing.InstantTaskExecutorRule
+import de.rki.coronawarnapp.ui.submission.SubmissionCountry
+import io.kotest.inspectors.forAll
+import io.kotest.inspectors.forAtLeastOne
+import io.kotest.inspectors.forAtMostOne
+import io.kotest.matchers.collections.shouldHaveSize
+import io.kotest.matchers.shouldBe
+import org.junit.Rule
+import org.junit.Test
+
+class SubmissionCountrySelectViewModelTest {
+    @get:Rule
+    val instantTaskExecRule = InstantTaskExecutorRule()
+
+    @Test
+    fun testFetchCountries() {
+        val viewModel = SubmissionCountrySelectViewModel()
+
+        viewModel.fetchCountries()
+        // TODO: implement proper test one backend is merged
+        viewModel.countries.value!!.shouldHaveSize(2)
+    }
+
+    @Test
+    fun testUpdateCountryCheckedState() {
+        val viewModel = SubmissionCountrySelectViewModel()
+
+        viewModel.fetchCountries()
+
+        viewModel.updateCountryCheckedState(SubmissionCountry("IT", true))
+        viewModel.countries.value!!.forAtMostOne {
+            it.countryCode shouldBe "IT"
+            it.selected shouldBe true
+        }
+
+        viewModel.updateCountryCheckedState(SubmissionCountry("IT", false))
+        viewModel.countries.value!!.forAtLeastOne {
+            it.countryCode shouldBe "IT"
+            it.selected shouldBe false
+        }
+    }
+
+    @Test
+    fun testNoInfoClickRemovesSelections() {
+        val viewModel = SubmissionCountrySelectViewModel()
+
+        viewModel.fetchCountries()
+
+        viewModel.updateCountryCheckedState(SubmissionCountry("IT", true))
+        viewModel.updateCountryCheckedState(SubmissionCountry("ES", true))
+        viewModel.countries.value!!.forAll { it.selected shouldBe true }
+
+        viewModel.noInfoClick()
+
+        viewModel.countries.value!!.forAll { it.selected shouldBe false }
+    }
+}