Spec for tool config apis (actions#3)

* creating an initial branch for config apis spec

* Add package specs

* mkdirP should return promise

* Which should return a promise

* Respond to feedback

* export => exportVariable

* Respond to feedback on spec

* Remove code for now

* trailing space

* Clarify throwing

docs/package-specs.md

@@ -0,0 +1,200 @@
+# Package Specs
+
+In order to support the node-config action, I propose adding the following into 4 libraries (tool-cache, core, io, exec), with tool-cache having dependencies on the other 3 libs:
+
+### Core spec
+
+Holds all the functions necessary for interacting with the runner/environment.
+
+```
+// Logging functions
+export function debug(message: string): void
+export function warning(message: string): void
+export function error(message: string): void
+
+/**
+ * Interface for exportVariable options
+ */
+export interface ExportOptions {
+    /** Optional. Whether the variable should be marked as secret (will be masked from logs). Defaults to false */
+    isSecret?: bool;
+}
+
+/**
+ * sets env variable for this action and future actions in the job
+ *
+ * @param name      the name of the variable to set
+ * @param val       the value of the variable
+ * @param options   optional. See ExportOptions.
+ */
+export function exportVariable(name: string, val: string, options?: ExportOptions): void
+
+/**
+ * Interface for getInput options
+ */
+export interface InputOptions {
+    /** Optional. Whether the input is required. If required and not present, will throw. Defaults to false */
+    required?: bool;
+}
+
+/**
+ * Gets the value of an input.  The value is also trimmed.
+ * 
+ * @param     name     name of the input to get
+ * @param     options  optional. See InputOptions.
+ * @returns   string
+ */
+export function getInput(name: string, options?: InputOptions): string | undefined
+
+/**
+ * fail the action
+ * @param message 
+ */
+export function setFailure(message: string): void
+```
+
+### IO spec
+
+Holds all the functions necessary for file system manipulation (cli scenarios, not fs replacements):
+
+```
+/**
+ * Interface for cp/mv options
+ */
+export interface CopyOptions {
+    /** Optional. Whether to recursively copy all subdirectories. Defaults to false */
+    recursive?: boolean;
+    /** Optional. Whether to overwrite existing files in the destination. Defaults to true */
+    force?: boolean;
+}
+
+/**
+ * Copies a file or folder.
+ * 
+ * @param     source    source path
+ * @param     dest      destination path
+ * @param     options   optional. See CopyOptions.
+ */
+export function cp(source: string, dest: string, options?: CopyOptions): Promise<void>
+
+/**
+ * Remove a path recursively with force
+ * 
+ * @param     path     path to remove
+ */
+export function rmRF(path: string): Promise<void>
+
+/**
+ * Make a directory.  Creates the full path with folders in between
+ * 
+ * @param     p       path to create
+ * @returns   Promise<void>
+ */
+export function mkdirP(p: string): Promise<void>
+
+/**
+ * Moves a path.
+ *
+ * @param     source    source path
+ * @param     dest      destination path
+ * @param     options   optional. See CopyOptions.
+ */
+export function mv(source: string, dest: string, options?: CopyOptions): Promise<void>
+
+/**
+ * Interface for which options
+ */
+export interface WhichOptions {
+    /** Optional. Whether to check if tool exists. If true, will throw if it fails. Defaults to false */
+    check?: boolean;
+}
+
+/**
+ * Returns path of a tool had the tool actually been invoked.  Resolves via paths.
+ * 
+ * @param     tool              name of the tool
+ * @param     options           optional. See WhichOptions.
+ * @returns   Promise<string>   path to tool
+ */
+export function which(tool: string, options?: WhichOptions): Promise<string>
+```
+
+### Exec spec
+
+Holds all the functions necessary for running the tools node-config depends on (aka 7-zip and tar)
+
+```
+/**
+ * Interface for exec options
+ */
+export interface IExecOptions
+
+/**
+* Exec a command.
+* Output will be streamed to the live console.
+* Returns promise with return code
+* 
+* @param     commandLine        command to execute
+* @param     args               optional additional arguments
+* @param     options            optional exec options.  See IExecOptions
+* @returns   Promise<number>    return code
+*/
+export function exec(commandLine: string, args?: string[], options?: IExecOptions): Promise<number> 
+```
+
+### Tool-Cache spec:
+
+Holds all the functions necessary for downloading and caching node.
+
+```
+/**
+ * Download a tool from an url and stream it into a file
+ *
+ * @param url       url of tool to download
+ * @returns         path to downloaded tool
+ */
+export async function downloadTool(url: string): Promise<string>
+
+/**
+ * Extract a .7z file
+ *
+ * @param file     path to the .7z file
+ * @param dest     destination directory. Optional.
+ * @returns        path to the destination directory
+ */
+export async function extract7z(file: string, dest?: string): Promise<string>
+
+/**
+ * Extract a tar
+ *
+ * @param file     path to the tar
+ * @param dest     destination directory. Optional.
+ * @returns        path to the destination directory
+ */
+export async function extractTar(file: string, destination?: string): Promise<string>
+
+/**
+ * Caches a directory and installs it into the tool cacheDir
+ *
+ * @param sourceDir    the directory to cache into tools
+ * @param tool          tool name
+ * @param version       version of the tool.  semver format
+ * @param arch          architecture of the tool.  Optional.  Defaults to machine architecture
+ */
+export async function cacheDir(sourceDir: string, tool: string, version: string, arch?: string): Promise<string>
+
+/**
+ * finds the path to a tool in the local installed tool cache
+ *
+ * @param toolName      name of the tool
+ * @param versionSpec   version of the tool
+ * @param arch          optional arch.  defaults to arch of computer
+ */
+export function find(toolName: string, versionSpec: string, arch?: string): string
+
+/**
+ * Prepends inputPath to the PATH
+ * @param inputPath
+ */
+export function addPath(inputPath: string): void
+```