Validate NuGet package names with the NuGet API

src/actions/vstudio/vs2010_nuget.lua

@@ -41,6 +41,36 @@
 	end
 
 
+	local validatedPackages = {}
+
+	function nuget2010.validatePackages(prj)
+		if #prj.nuget == 0 then
+			return
+		end
+
+		for _, package in ipairs(prj.nuget) do
+			local id = nuget2010.packageId(package)
+			local version = nuget2010.packageVersion(package)
+
+			if not validatedPackages[id] then
+				printf("Examining NuGet package '%s'...", id)
+				io.flush()
+
+				local response, err, code = http.get(string.format("https://api.nuget.org/v3/registration1/%s/index.json", id:lower()))
+
+				if err ~= "OK" then
+					if code == 404 then
+						p.error("NuGet package '%s' for project '%s' couldn't be found in the repository", id, prj.name)
+					else
+						p.error("NuGet API error (%d)\n%s", code, err)
+					end
+				end
+			end
+			validatedPackages[id] = package
+		end
+	end
+
+
 --
 -- Generates the packages.config file.
 --

src/base/validation.lua

@@ -61,6 +61,7 @@
 			m.actionSupportsKind,
 			m.projectRulesExist,
 			m.projectValuesInScope,
+			m.projectNuGetPackages,
 		}
 	end
 
@@ -223,6 +224,11 @@
 	end
 
 
+	function m.projectNuGetPackages(prj)
+		p.vstudio.nuget2010.validatePackages(prj)
+	end
+
+
 	function m.uniqueProjectIds(wks)
 		local uuids = {}
 		for prj in p.workspace.eachproject(wks) do