Add integration test

Author: mihaimaruseac

test/integration/tests/3899-dont-rebuild-sublibraries/Main.hs

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+import Control.Monad (unless)
+import Data.List (isInfixOf)
+import StackTest
+
+main :: IO ()
+main = do
+  stack ["clean"]
+  stack ["build"]
+  res <- compilingModulesLines . snd <$> stackStderr ["build"]
+  unless (null res) $ fail "Stack recompiled code"
+
+-- Returns the lines where a module is compiled
+compilingModulesLines :: String -> [String]
+compilingModulesLines = filter (isInfixOf " Compiling ") . lines

test/integration/tests/3899-dont-rebuild-sublibraries/files/Setup.hs

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+import Distribution.Simple
+main = defaultMain

test/integration/tests/3899-dont-rebuild-sublibraries/files/files.cabal

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+name:           files
+version:        0.1.0.0
+build-type:     Simple
+cabal-version:  >= 2.0
+
+library
+  hs-source-dirs:   src
+  exposed-modules:  Lib
+  build-depends:    base, lib
+  default-language: Haskell2010
+
+library lib
+  hs-source-dirs:   src-internal
+  exposed-modules:  Internal
+  build-depends:    base
+  default-language: Haskell2010
+
+executable exe
+  hs-source-dirs:   src-exe
+  main-is:          Main.hs
+  build-depends:    base, files
+  default-language: Haskell2010

test/integration/tests/3899-dont-rebuild-sublibraries/files/src-exe/Main.hs

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+module Main where
+
+import Lib
+
+main :: IO ()
+main = do
+  putStrLn "hello world"

test/integration/tests/3899-dont-rebuild-sublibraries/files/src-internal/Internal.hs

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+module Internal where

test/integration/tests/3899-dont-rebuild-sublibraries/files/src/Lib.hs

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+module Lib where
+
+import Internal

test/integration/tests/3899-dont-rebuild-sublibraries/files/stack.yaml

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+resolver: ghc-8.2.2
+extra-deps:
+- stm-2.4.4.1
+- mtl-2.2.1