Merge pull request #119 from MagiMaster/context2

Add Context object to lifecycle hooks and it blocks

Author: MagiMaster

CHANGELOG.md

@@ -5,6 +5,9 @@
   * `beforeAll` now runs on entering the block, rather than on the first `it` encountered after entering the block. The major difference for the moment is that a `beforeAll` will now run even if there are no `it` blocks under it, which is now consistent with how `afterAll` worked.
   * `beforeAll` and `afterAll` now report errors by creating a dummy node in the results to contain the error. Previously, errors in `afterAll` were not reported.
   * A failure in a `beforeAll` block will now halt all further test execution within its enclosing `describe` block except for any remaining `beforeAll` blocks and any `afterAll` blocks. Multiple `beforeAll` or `afterAll` blocks within one `describe` block should not count on running in any specific order. `afterAll` blocks should account for the possibility of a partially setup state when cleaning up.
+* Add a context object visible from lifecycle hooks and `it` blocks. This is a write-once store for whatever you need to communicate between hooks and tests. It can be ignored until you need it.
+  * In particular, you can usually just use upvalues to comminucate between hooks and tests, but that won't work if your hooks are in a separate file (e.g. `init.spec.lua`).
+  * Also, this provides a cleaner alternative to extraEnvironment for passing along helper functions to large numbers of tests as the context can be scoped to particular directories as needed.
 
 ## 0.3.0 (2020-06-12)
 * Remove the `try` node type.

src/TestRunner.lua

@@ -70,9 +70,16 @@ function TestRunner.runPlanNode(session, planNode, lifecycleHooks)
 			errorMessage = messagePrefix .. message .. "\n" .. debug.traceback()
 		end
 
-		local nodeSuccess, nodeResult = xpcall(callback, function(message)
-			return messagePrefix .. message .. "\n" .. debug.traceback()
-		end)
+		local context = session:getContext()
+
+		local nodeSuccess, nodeResult = xpcall(
+			function()
+				callback(context)
+			end,
+			function(message)
+				return messagePrefix .. message .. "\n" .. debug.traceback()
+			end
+		)
 
 		-- If a node threw an error, we prefer to use that message over
 		-- one created by fail() if it was set.

src/TestSession.lua

@@ -9,6 +9,7 @@
 
 local TestEnum = require(script.Parent.TestEnum)
 local TestResults = require(script.Parent.TestResults)
+local Context = require(script.Parent.Context)
 
 local TestSession = {}
 
@@ -23,6 +24,7 @@ function TestSession.new(plan)
 	local self = {
 		results = TestResults.new(plan),
 		nodeStack = {},
+		contextStack = {},
 		hasFocusNodes = false
 	}
 
@@ -95,11 +97,13 @@ end
 ]]
 function TestSession:pushNode(planNode)
 	local node = TestResults.createNode(planNode)
-
 	local lastNode = self.nodeStack[#self.nodeStack] or self.results
+	local lastContext = self.contextStack[#self.contextStack]
+	local context = Context.new(lastContext)
 
 	table.insert(lastNode.children, node)
 	table.insert(self.nodeStack, node)
+	table.insert(self.contextStack, context)
 end
 
 --[[
@@ -108,6 +112,15 @@ end
 function TestSession:popNode()
 	assert(#self.nodeStack > 0, "Tried to pop from an empty node stack!")
 	table.remove(self.nodeStack, #self.nodeStack)
+	table.remove(self.contextStack, #self.contextStack)
+end
+
+--[[
+	Gets the Context object for the current node.
+]]
+function TestSession:getContext()
+	assert(#self.contextStack > 0, "Tried to get context from an empty stack!")
+	return self.contextStack[#self.contextStack]
 end
 
 --[[
@@ -172,7 +185,9 @@ function TestSession:setError(message)
 end
 
 --[[
-	Add a dummy node below the current one to hold an error message.
+	Add a dummy child node to the current node to hold the given error. This
+	allows an otherwise empty describe node to report an error in a more natural
+	way.
 ]]
 function TestSession:addDummyError(phrase, message)
 	self:pushNode({type = TestEnum.NodeType.It, phrase = phrase})

tests/passing/context.spec.lua

@@ -0,0 +1,27 @@
+-- luacheck: globals describe beforeAll beforeEach it expect afterEach afterAll
+
+return function()
+	describe("context is passed between lifecycle hooks and it blocks", function()
+		beforeAll(function(context)
+			context.a = 1
+		end)
+
+		beforeEach(function(context)
+			context.b = 1
+		end)
+
+		it("before hooks should run", function(context)
+			expect(context.a).to.equal(1)
+			expect(context.b).to.equal(1)
+		end)
+
+		afterEach(function(context)
+			expect(context.b).to.equal(1)
+		end)
+
+		afterAll(function(context)
+			-- Failures in afterAll aren't reported.
+			expect(context.a).to.equal(1)
+		end)
+	end)
+end

tests/passing/describeAndContext.spec.lua

@@ -0,0 +1,7 @@
+-- luacheck: globals describe expect
+
+return function()
+	describe("this shouldn't be able to access context", function(context)
+		expect(context).to.never.be.ok()
+	end)
+end

tests/passing/nestedContext.spec.lua

@@ -0,0 +1,25 @@
+-- luacheck: globals describe beforeAll it expect
+
+return function()
+	describe("setting context here", function()
+		beforeAll(function(context)
+			context.a = 1
+		end)
+
+		describe("should apply here", function()
+			beforeAll(function(context)
+				context.b = context.a + 1
+			end)
+
+			it("should see a and b", function(context)
+				expect(context.a).to.equal(1)
+				expect(context.b).to.equal(2)
+			end)
+		end)
+
+		it("should not see b here", function(context)
+			expect(context.a).to.equal(1)
+			expect(context.b).to.never.be.ok()
+		end)
+	end)
+end