Build ICU for instrumentation-test machine

Signed-off-by: utzcoz <utzcoz@outlook.com>

.github/workflows/tests.yml

@@ -44,8 +44,7 @@ jobs:
           make -j4
           make install
 
-      - name: Install Ninja (Linux)
-        if: runner.os =='Linux'
+      - name: Install Ninja
         run: sudo apt-get install ninja-build
 
       - name: Build
@@ -86,7 +85,6 @@ jobs:
           key: ${{ runner.os }}-${{ runner.arch }}-icu-${{ hashFiles('nativeruntime/external/icu/**') }}
 
       - name: Install Ninja
-        if: runner.os =='Linux'
         run: sudo apt-get install ninja-build
 
       - name: Run unit tests
@@ -127,6 +125,24 @@ jobs:
         with:
           java-version: 11.0.8
 
+      - name: Install build tools
+        run: brew install ninja
+
+      - name: Cache ICU build output
+        id: cache-icu
+        uses: actions/cache@v2
+        with:
+          path: ~/icu-bin
+          key: ${{ runner.os }}-${{ runner.arch }}-icu-${{ hashFiles('nativeruntime/external/icu/**') }}
+
+      - name: Build ICU
+        if: steps.cache-icu.outputs.cache-hit != 'true'
+        run: |
+          cd nativeruntime/external/icu/icu4c/source
+          ./runConfigureICU MacOSX --enable-static --prefix=$HOME/icu-bin
+          make -j4
+          make install
+
       # Determine what emulator image to use. We run all API 29+ emulators using
       # the google_apis image
       - name: Determine emulator target
@@ -147,7 +163,7 @@ jobs:
           target: ${{ steps.determine-target.outputs.TARGET }}
           profile: Nexus One
           emulator-build: 7425822 # https://github.com/ReactiveCircus/android-emulator-runner/issues/160
-          script: ./gradlew connectedCheck
+          script: ICU_ROOT_DIR=$HOME/icu-bin SKIP_ERRORPRONE=true SKIP_JAVADOC=true ./gradlew connectedCheck
 
       - name: Upload test results
         if: always()