Separate rustfmt into multiple crates (#3998)

Author: topecongiro

.github/workflows/windows.yml

@@ -62,3 +62,9 @@ jobs:
     - name: 'test ignored'
       run: cargo test -- --ignored
       shell: cmd
+    - name: 'test rustfmt-core'
+      run: cargo test --manifest-path rustfmt-core/Cargo.toml
+      shell: cmd
+    - name: 'test rustfmt-core ignored'
+      run: cargo test --manifest-path rustfmt-core/Cargo.toml -- --ignored
+      shell: cmd

.travis.yml

@@ -46,7 +46,7 @@ matrix:
 script:
   - |
     if [ -z ${INTEGRATION} ]; then
-      cargo build && cargo test && cargo test -- --ignored
+      cargo build && cargo test && cargo test -- --ignored && cargo test --manifest-path rustfmt-core/Cargo.toml && cargo test --manifest-path rustfmt-core/Cargo.toml -- --ignored
     else
       ./ci/integration.sh
     fi