Add test-cases for extracting build-info, even if a component failed to build

cabal-testsuite/PackageTests/ShowBuildInfo/A/remove-outdated.test.hs

@@ -3,7 +3,6 @@ import           Test.Cabal.Prelude
 import           Test.Cabal.DecodeShowBuildInfo
 import           Test.Cabal.Plan
 import           Control.Monad.Trans.Reader
-import           System.Directory
 
 main = cabalTest $ do
   runShowBuildInfo ["exe:A"]

cabal-testsuite/PackageTests/ShowBuildInfo/CompileFail/CompileFail.cabal

+cabal-version:      3.0
+name:               CompileFail
+version:            0.1.0.0
+build-type:         Simple
+
+library
+    exposed-modules:  MyLib
+    build-depends:    base
+    hs-source-dirs:   src
+    default-language: Haskell2010
+
+library failing
+    exposed-modules:  MyLib2
+    build-depends:    base
+    hs-source-dirs:   src
+    default-language: Haskell2010
+
+test-suite CompileFail-test
+    default-language: Haskell2010
+    type:             exitcode-stdio-1.0
+    hs-source-dirs:   test
+    main-is:          Main.hs
+    build-depends:    base, CompileFail
+
+executable CompileFail-exe
+    default-language: Haskell2010
+    hs-source-dirs:   app
+    main-is:          Main.hs
+    build-depends:    base, failing

cabal-testsuite/PackageTests/ShowBuildInfo/CompileFail/app/Main.hs

+module Main where
+
+import MyLib2 (someFunc2)
+
+main :: IO ()
+main = someFunc2

cabal-testsuite/PackageTests/ShowBuildInfo/CompileFail/cabal.project

+packages: ./

cabal-testsuite/PackageTests/ShowBuildInfo/CompileFail/compile-fail.out

+# cabal build
+Resolving dependencies...
+Build profile: -w ghc-<GHCVER> -O1
+In order, the following will be built:
+ - CompileFail-0.1.0.0 (lib) (first run)
+ - CompileFail-0.1.0.0 (test:CompileFail-test) (first run)
+Configuring library for CompileFail-0.1.0.0..
+Preprocessing library for CompileFail-0.1.0.0..
+Building library for CompileFail-0.1.0.0..
+Configuring test suite 'CompileFail-test' for CompileFail-0.1.0.0..
+Preprocessing test suite 'CompileFail-test' for CompileFail-0.1.0.0..
+Building test suite 'CompileFail-test' for CompileFail-0.1.0.0..
+# cabal build
+Build profile: -w ghc-<GHCVER> -O1
+In order, the following will be built:
+ - CompileFail-0.1.0.0 (lib:failing) (first run)
+ - CompileFail-0.1.0.0 (exe:CompileFail-exe) (first run)
+Configuring library 'failing' for CompileFail-0.1.0.0..
+Preprocessing library 'failing' for CompileFail-0.1.0.0..
+Building library 'failing' for CompileFail-0.1.0.0..
+cabal: Failed to build CompileFail-0.1.0.0 because it depends on CompileFail-0.1.0.0 which itself failed to build.
+Failed to build CompileFail-0.1.0.0-inplace-failing.

cabal-testsuite/PackageTests/ShowBuildInfo/CompileFail/compile-fail.test.hs

+{-# LANGUAGE OverloadedStrings #-}
+import           Test.Cabal.Prelude
+import           Test.Cabal.DecodeShowBuildInfo
+import           Test.Cabal.Plan
+import           Control.Monad.Trans.Reader
+
+main = cabalTest $ do
+  -- Leaf component fails to compile, should still dump
+  -- build info for both components.
+  fails $ runShowBuildInfo ["test:CompileFail-test"]
+  withPlan $ do
+    -- Lib has to be built, thus info is dumped
+    assertComponent "CompileFail" mainLib
+      defCompAssertion
+        { modules = ["MyLib"]
+        , sourceDirs = ["src"]
+        }
+
+    -- Build Info is still dumped, although compilation failed
+    assertComponent "CompileFail" (test "CompileFail-test")
+      defCompAssertion
+        { sourceFiles = ["Main.hs"]
+        , sourceDirs = ["test"]
+        }
+
+  fails $ runShowBuildInfo ["exe:CompileFail-exe"]
+  withPlan $ do
+    -- Internal Lib has to be built, thus info is dumped
+    assertComponent "CompileFail" (lib "failing")
+      defCompAssertion
+        { modules = ["MyLib2"]
+        , sourceDirs = ["src"]
+        }
+    -- However, since the internal lib failed to compile
+    -- we can not have executable build information.
+    Just plan <- fmap testPlan ask
+    let fp = buildInfoFile plan "CompileFail" (exe "CompileFail-exe")
+    shouldNotExist fp

cabal-testsuite/PackageTests/ShowBuildInfo/CompileFail/src/MyLib.hs

+module MyLib (someFunc) where
+
+someFunc :: IO ()
+someFunc = putStrLn "someFunc"

cabal-testsuite/PackageTests/ShowBuildInfo/CompileFail/src/MyLib2.hs

+module MyLib2 (someFunc2) where
+
+someFunc2 :: IO ()
+-- Intentional typo, should fail to compile
+someFunc2 = putStrn "someFunc"
+--          ^^------- missing 'L'

cabal-testsuite/PackageTests/ShowBuildInfo/CompileFail/test/Main.hs

+module Main (main) where
+
+main :: IO ()
+-- Intentional typo, should fail to compile
+main = putStrn "Test suite not yet implemented."
+--          ^^------- missing 'L'

cabal-testsuite/src/Test/Cabal/DecodeShowBuildInfo.hs

@@ -111,7 +111,7 @@ defCompAssertion = ComponentAssertion
   , modules = []
   , sourceFiles = []
   , sourceDirs = []
-  , compType = mempty
+  , compType = ""
   }
 
 -- | Assert common build information, such as compiler location, compiler version