Fix #29: new input cabal-update: false to skip 'cabal update' (#146)

This commit introduces a new boolean input `cabal-update` that defaults to `true`.  
If set to `false`, the `cabal update` step will be skipped.

The new flag `cabal-update` is proper boolean, it only accepts the YAML 1.2 truth values `true` and `false` (also in captial and uppercase).
This is contrast to other "boolean" flags that are "unset" by default and can be "set" with any non-empty string.

To test that `cabal update` happens, this commit also introduces a new Haskell test project into CI that depends on a common Hackage package (`base-orphans`).

Original commits:
* Fix #29: new input 'cabal-update: false' to turn off 'cabal update'
* Test 'cabal-update: false'
* README: Add 'cabal-update' to table of inputs
* Accept YAML 1.2 booleans as values for 'cabal-update'
* CI: test 'cabal-update: true': project with Hackage dependency
* Default value for 'cabal-update'
* CI: use cabal_update (underscore) in matrix
* Fixup: project with Hackage dependency
* Work around #158
* Extra clarification of boolean vs "boolean" inputs

.github/workflows/workflow.yml

@@ -41,10 +41,13 @@ jobs:
         os: [ubuntu-latest, macOS-latest, windows-latest]
         ghc: ["latest", "8.4.4"]
         cabal: ["latest", "3.2.0.0"]
+        cabal_update: ["false"]
+        # The following tests do not set 'cabal-update', which defaults to 'true' then.
         include:
           - os: ubuntu-latest
             ghc: "8.2.2"
             cabal: "2.4.1.0"
+            cabal_update: "false"
           - os: ubuntu-18.04
             ghc: "7.4.1"
             cabal: "3.4"
@@ -68,24 +71,36 @@ jobs:
             cabal: "3.6"
     steps:
       - uses: actions/checkout@v3
+
       - uses: ./setup
         with:
           ghc-version: ${{ matrix.ghc }}
           cabal-version: ${{ matrix.cabal }}
+          cabal-update: ${{ matrix.cabal_update }}
+
       - name: Test runghc
         run: |
           runghc --version
           runghc __tests__/hello.hs
+
       - name: Build test project
         working-directory: setup/__tests__/project
         run: cabal build
+
       - name: Run test project
         working-directory: setup/__tests__/project
         run: cabal run
+
+      - name: Build and run test with Hackage dependency
+        if:   ${{ matrix.cabal_update != 'false' }}
+        working-directory: setup/__tests__/project-with-hackage-dependency
+        run:  cabal build && cabal run
+
       - name: Show installed versions
         run: |
           cabal --version
           ghc --version
+
       - name: Confirm installed and expected versions match
         shell: bash
         # check that if given in the matrix, the actual version matches:

setup/README.md

@@ -98,18 +98,22 @@ jobs:
 
 ## Inputs
 
-| Name              | Required | Description                                                                                                                              | Type      | Default     |
-| ----------------- | :------: | ---------------------------------------------------------------------------------------------------------------------------------------- | --------- | ----------- |
-| `ghc-version`     |          | GHC version to use, ex. `latest`                                                                                                         | string    | latest      |
-| `cabal-version`   |          | Cabal version to use, ex. `3.4`                                                                                                          | string    | latest      |
-| `stack-version`   |          | Stack version to use, ex. `latest`. Stack will only be installed if `enable-stack` is set.                                               | string    | latest      |
-| `enable-stack`    |          | If set, will setup Stack.                                                                                                                | "boolean" | false/unset |
-| `stack-no-global` |          | If set, enable-stack must be set. Prevents installing GHC and Cabal globally                                                             | "boolean" | false/unset |
-| `stack-setup-ghc` |          | If set, enable-stack must be set. Runs stack setup to install the specified GHC. (Note: setting this does _not_ imply `stack-no-global`) | "boolean" | false/unset |
-| `disable-matcher` |          | If set, disables match messages from GHC as GitHub CI annotations                                                                        | "boolean" | false/unset |
+| Name              | Description                                                                                                                                 | Type      | Default     |
+| ----------------- | ------------------------------------------------------------------------------------------------------------------------------------------- | --------- | ----------- |
+| `ghc-version`     | GHC version to use, e.g. `9.2` or `9.2.4`.                                                                                                  | `string`  | `latest`    |
+| `cabal-version`   | Cabal version to use, e.g. `3.4`.                                                                                                           | `string`  | `latest`    |
+| `stack-version`   | Stack version to use, e.g. `latest`. Stack will only be installed if `enable-stack` is set.                                                 | `string`  | `latest`    |
+| `enable-stack`    | If set, will setup Stack.                                                                                                                   | "boolean" | false/unset |
+| `stack-no-global` | If set, `enable-stack` must be set. Prevents installing GHC and Cabal globally.                                                             | "boolean" | false/unset |
+| `stack-setup-ghc` | If set, `enable-stack` must be set. Runs stack setup to install the specified GHC. (Note: setting this does _not_ imply `stack-no-global`.) | "boolean" | false/unset |
+| `disable-matcher` | If set, disables match messages from GHC as GitHub CI annotations.                                                                          | "boolean" | false/unset |
+| `cabal-update`    | If set to `false`, skip `cabal update` step.                                                                                                | `boolean` | `true`      |
 
 Note: "boolean" types are set/unset, not true/false.
 That is, setting any "boolean" to a value other than the empty string (`""`) will be considered true/set.
+However, to avoid confusion and for forward compatibility, it is still recommended to **only use value `true` to set a "boolean" flag.**
+
+In contrast, a proper `boolean` input like `cabal-update` only accepts values `true` and `false`.
 
 ## Outputs
 

setup/__tests__/project-with-hackage-dependency/Main.hs

@@ -0,0 +1,4 @@
+module Main where
+
+main :: IO ()
+main = putStrLn "Hello, Hackage!"

setup/__tests__/project-with-hackage-dependency/Setup.hs

@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain

setup/__tests__/project-with-hackage-dependency/project-with-hackage-dependency.cabal

@@ -0,0 +1,11 @@
+cabal-version:       >=1.10
+name:                project-with-hackage-dependency
+version:             0.1.0.0
+build-type:          Simple
+
+executable project
+  main-is:             Main.hs
+  build-depends:       base
+                       -- Add a package from hackage here to see whether `cabal update` ran.
+                     , base-orphans
+  default-language:    Haskell2010

setup/action.yml

@@ -16,16 +16,23 @@ inputs:
     default: 'latest'
   enable-stack:
     required: false
-    description: 'If specified, will setup Stack'
+    description: 'If specified, will setup Stack.'
   stack-no-global:
     required: false
-    description: 'If specified, enable-stack must be set. Prevents installing GHC and Cabal globally'
+    description: 'If specified, enable-stack must be set. Prevents installing GHC and Cabal globally.'
   stack-setup-ghc:
     required: false
-    description: 'If specified, enable-stack must be set. Will run stack setup to install the specified GHC'
+    description: 'If specified, enable-stack must be set. Will run stack setup to install the specified GHC.'
+  cabal-update:
+    required: false
+    default: true
+    description: 'Set to `false` to prevent `cabal update` from being run.'
+    # Note: 'cabal-update' only accepts 'true' and 'false' as values.
+    # This is different from the other flags ('enable-stack', 'disable-matcher' etc.)
+    # which are true as soon as they are not null.
   disable-matcher:
     required: false
-    description: 'If specified, disables match messages from GHC as GitHub CI annotations'
+    description: 'If specified, disables match messages from GHC as GitHub CI annotations.'
 outputs:
   ghc-path:
     description: 'The path of the ghc executable _directory_'

setup/src/opts.ts

@@ -24,7 +24,7 @@ export interface ProgramOpt {
 
 export interface Options {
   ghc: ProgramOpt;
-  cabal: ProgramOpt;
+  cabal: ProgramOpt & {update: boolean};
   stack: ProgramOpt & {setup: boolean};
   general: {matcher: {enable: boolean}};
 }
@@ -83,6 +83,27 @@ export function releaseRevision(version: string, tool: Tool, os: OS): string {
   return result;
 }
 
+/**
+ * Convert a string input to a boolean according to the YAML 1.2 "core schema" specification.
+ * Supported boolean renderings: `true | True | TRUE | false | False | FALSE` .
+ * ref: https://yaml.org/spec/1.2/spec.html#id2804923
+ * Adapted from: https://github.com/actions/toolkit/commit/fbdf27470cdcb52f16755d32082f1fee0bfb7d6d#diff-f63fb32fca85d8e177d6400ce078818a4815b80ac7a3319b60d3507354890992R94-R115
+ *
+ * @param     name     name of the input
+ * @param     val      supposed string representation of a boolean
+ * @returns   boolean
+ */
+export function parseYAMLBoolean(name: string, val: string): boolean {
+  const trueValue = ['true', 'True', 'TRUE'];
+  const falseValue = ['false', 'False', 'FALSE'];
+  if (trueValue.includes(val)) return true;
+  if (falseValue.includes(val)) return false;
+  throw new TypeError(
+    `Action input "${name}" does not meet YAML 1.2 "Core Schema" specification: \n` +
+      `Supported boolean values: \`true | True | TRUE | false | False | FALSE\``
+  );
+}
+
 export function getOpts(
   {ghc, cabal, stack}: Defaults,
   os: OS,
@@ -93,6 +114,14 @@ export function getOpts(
   const stackSetupGhc = (inputs['stack-setup-ghc'] || '') !== '';
   const stackEnable = (inputs['enable-stack'] || '') !== '';
   const matcherDisable = (inputs['disable-matcher'] || '') !== '';
+  // Andreas, 2023-01-05, issue #29:
+  // 'cabal-update' has a default value, so we should get a proper boolean always.
+  // Andreas, 2023-01-06: This is not true if we use the action as a library.
+  // Thus, need to patch with default value here.
+  const cabalUpdate = parseYAMLBoolean(
+    'cabal-update',
+    inputs['cabal-update'] || 'true'
+  );
   core.debug(`${stackNoGlobal}/${stackSetupGhc}/${stackEnable}`);
   const verInpt = {
     ghc: inputs['ghc-version'] || ghc.version,
@@ -136,7 +165,8 @@ export function getOpts(
         os,
         cabalEnable // if true: inform user about resolution
       ),
-      enable: cabalEnable
+      enable: cabalEnable,
+      update: cabalUpdate
     },
     stack: {
       raw: verInpt.stack,

setup/src/setup-haskell.ts

@@ -73,7 +73,7 @@ export default async function run(
           // https://github.com/haskell/cabal/issues/6823
           // await exec('cabal user-config update');
         }
-        if (!opts.stack.enable) await exec('cabal update');
+        if (opts.cabal.update && !opts.stack.enable) await exec('cabal update');
       });
 
     core.info(`##[add-matcher]${path.join(__dirname, '..', 'matcher.json')}`);