refactor: Introducing Environments

Tests/StencilTests/EnvironmentSpec.swift

@@ -0,0 +1,41 @@
+import Spectre
+import Stencil
+
+
+func testEnvironment() {
+  describe("Environment") {
+    let environment = Environment(loader: ExampleLoader())
+
+    $0.it("can load a template from a name") {
+      let template = try environment.loadTemplate(name: "example.html")
+      try expect(template.name) == "example.html"
+    }
+
+    $0.it("can load a template from a names") {
+      let template = try environment.loadTemplate(names: ["first.html", "example.html"])
+      try expect(template.name) == "example.html"
+    }
+
+    $0.it("can render a template from a string") {
+      let result = try environment.renderTemplate(string: "Hello World")
+      try expect(result) == "Hello World"
+    }
+
+    $0.it("can render a template from a file") {
+      let result = try environment.renderTemplate(name: "example.html")
+      try expect(result) == "Hello World!"
+    }
+  }
+}
+
+
+
+fileprivate class ExampleLoader: Loader {
+  func loadTemplate(name: String, environment: Environment) throws -> Template {
+    if name == "example.html" {
+      return Template(templateString: "Hello World!", environment: environment, name: name)
+    }
+
+    throw TemplateDoesNotExist(templateNames: [name], loader: self)
+  }
+}