[#1] Fail if all files are reset to committed version.

spec/test_spec.rb

@@ -19,8 +19,9 @@ describe FormatStaged do
   it 'updates staged file and working copy' do
     repo.set_content 'test.test', 'a=b'
     repo.stage 'test.test'
-    repo.run_formatter
+    success = repo.run_formatter
 
+    expect(success).to be_truthy
     expect(repo.get_staged('test.test')).to eq('a = b')
     expect(repo.get_content('test.test')).to eq('a = b')
   end
@@ -29,8 +30,9 @@ describe FormatStaged do
     repo.set_content 'test.test', "x=y\na=b\n"
     repo.stage 'test.test'
     repo.set_content 'test.test', 'abc'
-    repo.run_formatter
+    success = repo.run_formatter
 
+    expect(success).to be_truthy
     expect(repo.get_content('test.test')).to eq('abc')
     expect(repo.get_staged('test.test')).to eq("x = y\na = b")
   end
@@ -39,8 +41,9 @@ describe FormatStaged do
     repo.set_content 'test.test', "x=y\n#stuff\n"
     repo.stage 'test.test'
     repo.set_content 'test.test', "x=y\n#stuff\nmore stuff\n"
-    repo.run_formatter
+    success = repo.run_formatter
 
+    expect(success).to be_truthy
     expect(repo.get_content('test.test')).to eq("x = y\n#stuff\nmore stuff")
     expect(repo.get_staged('test.test')).to eq("x = y\n#stuff")
   end
@@ -48,8 +51,24 @@ describe FormatStaged do
   it 'only touches files matching the given pattern' do
     repo.set_content 'test.other', 'x=y'
     repo.stage 'test.other'
-    repo.run_formatter
+    success = repo.run_formatter
 
+    expect(success).to be_truthy
     expect(repo.get_content('test.other')).to eq('x=y')
   end
+
+  it 'fails if files are changed to already comitted version' do
+    repo.file_in_tree 'test.test', 'x = y'
+    repo.set_content 'test.test', 'x=y'
+    repo.stage 'test.test'
+
+    success = repo.run_formatter
+
+    expect(success).to be_falsy
+    expect(repo.get_content('test.test')).to eq('x = y')
+  end
+
+  it 'succeeds if there are no staged files' do
+    expect(repo.run_formatter).to be_truthy
+  end
 end