(#3502) Add end to end tests around page size

Add tests to exercise the messages added for page sizes and ensure they
are behaving as expected.

tests/pester-tests/features/PageSize.Tests.ps1

@@ -0,0 +1,64 @@
+Describe 'Ensuring <Command> honours page size settings' -ForEach @(
+    @{
+        Command = 'search'
+    }
+) -Tag PageSize {
+    BeforeAll {
+        Initialize-ChocolateyTestInstall
+    }
+
+    Context 'Page size <ProvidedSize>' -ForEach @(
+        @{
+            ExpectedExitCode = 1
+            ProvidedSize = 0
+        }
+        @{
+            ExpectedExitCode = 1
+            ProvidedSize = 101
+        }
+        @{
+            ExpectedExitCode = 0
+            ProvidedSize = 1
+        }
+        @{
+            ExpectedExitCode = 0
+            ProvidedSize = 30
+        }
+        @{
+            ExpectedExitCode = 0
+            ProvidedSize = 40
+        }
+        @{
+            ExpectedExitCode = 0
+            ProvidedSize = 100
+        }
+    ) {
+        BeforeAll {
+            $Output = Invoke-Choco $Command --page-size $ProvidedSize
+        }
+
+        It 'Exits correctly (<ExpectedExitCode>)' {
+            $Output.ExitCode | Should -Be $ExpectedExitCode -Because $Output.String
+        }
+
+        It 'Outputs expected messages' {
+            $ExpectedMessage = if ($ExpectedExitCode -eq 1) {
+                "The page size has been specified to be $ProvidedSize packages. The page size cannot be lower than 1 package, and no larger than 100 packages."
+            } else {
+                if ($ProvidedSize -ne 30) {
+                    "The page size has been specified to be $ProvidedSize packages. There are known issues with some repositories when you use a page size other than 30."
+                }
+                # There are currently 43 test packages in the repository.
+                # Any number above this amount will not result in the below message.
+                if ($ProvidedSize -le 40) {
+                    "The threshold of $ProvidedSize packages, or package versions, per source has been met. Please refine your search, or specify a page number to retrieve more results."
+                }
+            }
+            foreach ($message in $ExpectedMessage) {
+                # The output here may contain duplicated line for the warning about non-30 page size.
+                # We have been unable to reproduce this output in any scenario other than in these tests.
+                $Output.Lines | Should -Contain $message -Because $Output.String
+            }
+        }
+    }
+}