travis: extract functionality to scripts

It's very advantageous to be able to run the Travis scripts locally. So
we extract them into separate scripts. They are explained in the README.

Closes #398.

.travis.yml

@@ -39,64 +39,10 @@ script:
 
     # Explicit set exercises' resolver only if it's not the current one.
     if [ "${CURRENT}" != "YES" ]; then
-        SET_RESOLVER="--resolver ${RESOLVER}"
+        export SET_RESOLVER="--resolver ${RESOLVER}"
     fi
 
-    test_exercise () {
-        stack test ${SET_RESOLVER} `# Select the correct resolver. `\
-                   --install-ghc   `# Download GHC if not in cache.`\
-                   --no-terminal   `# Terminal detection is broken.`\
-                   --pedantic      `# Enable -Wall and -Werror.    `
-    }
-
     for exercise in ${TRAVIS_BUILD_DIR}/exercises/*/ ; do
-        exercisename=$(basename "$exercise")
-        pushd ${exercise}
-
-        examplename="stub"
-        buildfolder="${TRAVIS_BUILD_DIR}/build/${exercisename}/${examplename}"
-        mkdir -p "${buildfolder}"
-        cp -rL stack.yaml package.yaml src test "${buildfolder}"
-
-        pushd $buildfolder
-
-        examplecache="${HOME}/.foldercache/${exercisename}/${examplename}/.stack-work"
-        mkdir -p "$examplecache"
-        ln -f -s "$examplecache"
-
-        if [ -f "${exercise}/.meta/DONT-TEST-STUB" ]; then
-            echo "only building stub"
-            stack build ${SET_RESOLVER} --install-ghc --no-terminal
-        else
-            echo "testing stub"
-            stack test ${SET_RESOLVER} --install-ghc --no-terminal --no-run-tests
-        fi
-
-        popd
-
-        if ! stat -t examples/*/ > /dev/null 2>&1; then
-            echo "No examples for ${exercise}!"
-            exit 1
-        else
-            for example in examples/*/ ; do
-                examplename=$(basename "$example")
-
-                buildfolder="${TRAVIS_BUILD_DIR}/build/${exercisename}/${examplename}"
-                mkdir -p "${buildfolder}"
-                cp -rL stack.yaml test ${example}/* "${buildfolder}"
-
-                pushd $buildfolder
-
-                examplecache="${HOME}/.foldercache/${exercisename}/${examplename}/.stack-work"
-                mkdir -p "$examplecache"
-                ln -f -s "$examplecache"
-
-                echo "testing ${example}"
-                test_exercise
-
-                popd
-            done
-        fi
-
-        popd
+        bin/test-stub $exercise
+        bin/test-all-examples $exercise
     done

README.md

@@ -138,17 +138,12 @@ a few seconds.
 
 First you need to provide an [example solution](#example-solution).
 
-Running `stack test --pedantic` compiles and runs the tests with
-`-Wall -Werror`, but unfortunately it doesn't recompile unchanged
-source code already compiled with warnings.
+We provide three scripts in the `bin` directory of this repository to run the tests.
+These are the same scripts as those used by Travis CI.
 
-To be really sure that everything compiles correctly without
-warnings, your must first run `stack clean`.
-
-```bash
-stack clean
-stack test --pedantic
-```
+* `test-example path/to/example/dir` runs the tests on a single example.
+* `test-all-examples path/to/exercise/dir` runs the tests on all examples for an exercise.
+* `test-stub path/to/exercise/dir` checks that the stub for the given exercise compiles.
 
 ### Running HLint
 All code in this repository should be as idiomatic as possible, so we

bin/test-all-examples

@@ -0,0 +1,20 @@
+#!/bin/sh
+
+set -e
+
+if [ $# -eq 0 ]; then
+    echo "usage: $0 /path/to/exercise"
+    exit 1
+fi
+
+exercisedir=$1
+
+if ! stat -t ${exercisedir}/examples/*/ > /dev/null 2>&1; then
+    echo "No examples for ${exercisedir}!"
+    exit 1
+else
+    mydir=$(dirname $0)
+    for example in ${exercisedir}/examples/*/ ; do
+        $mydir/test-example $example
+    done
+fi

bin/test-example

@@ -0,0 +1,35 @@
+#!/bin/sh
+
+if [ $# -eq 0 ]; then
+    echo "usage: $0 /path/to/exercise/example"
+    exit 1
+fi
+
+exampledir=$(cd "$1" && pwd)
+
+examplename=$(basename "$exampledir")
+exercisedir=$(cd "$exampledir/../.." && pwd)
+exercisename=$(basename "$exercisedir")
+xhaskell=$(cd "$(dirname "$0")/.." && pwd)
+
+buildfolder="${TRAVIS_BUILD_DIR:-$xhaskell}/build/${exercisename}/${examplename}"
+mkdir -p "${buildfolder}"
+cp -rL ${exercisedir}/stack.yaml ${exercisedir}/test ${exampledir}/* "${buildfolder}"
+
+cd $buildfolder
+
+if [ -n "$TRAVIS" ]; then
+    cachedir="$HOME"
+else
+    cachedir="$xhaskell"
+fi
+examplecache="${cachedir}/.foldercache/${exercisename}/${examplename}/.stack-work"
+mkdir -p "$examplecache"
+ln -f -s "$examplecache"
+
+echo "testing ${exampledir}"
+# SET_RESOLVER passed by .travis.yml - sets --resolver if not current.
+stack test ${SET_RESOLVER} `# Select the correct resolver. `\
+           --install-ghc   `# Download GHC if not in cache.`\
+           --no-terminal   `# Terminal detection is broken.`\
+           --pedantic      `# Enable -Wall and -Werror.    `

bin/test-stub

@@ -0,0 +1,35 @@
+#!/bin/sh
+
+if [ $# -eq 0 ]; then
+    echo "usage: $0 /path/to/exercise"
+    exit 1
+fi
+
+exercisedir=$(cd "$1" && pwd)
+exercisename=$(basename "$exercisedir")
+examplename="stub"
+xhaskell=$(cd "$(dirname "$0")/.." && pwd)
+
+buildfolder="${TRAVIS_BUILD_DIR:-$xhaskell}/build/${exercisename}/${examplename}"
+mkdir -p "${buildfolder}"
+cp -rL ${exercisedir}/stack.yaml ${exercisedir}/package.yaml ${exercisedir}/src ${exercisedir}/test "${buildfolder}"
+
+cd $buildfolder
+
+if [ -n "$TRAVIS" ]; then
+    cachedir="$HOME"
+else
+    cachedir="$xhaskell"
+fi
+examplecache="${cachedir}/.foldercache/${exercisename}/${examplename}/.stack-work"
+mkdir -p "$examplecache"
+ln -f -s "$examplecache"
+
+# SET_RESOLVER passed by .travis.yml - sets --resolver if not current.
+if [ -f "${exercisedir}/.meta/DONT-TEST-STUB" ]; then
+    echo "only building stub"
+    stack build ${SET_RESOLVER} --install-ghc --no-terminal
+else
+    echo "testing stub"
+    stack test ${SET_RESOLVER} --install-ghc --no-terminal --no-run-tests
+fi