diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 10e0bf2..22b850b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -13,8 +13,8 @@ permissions:
   contents: read
 
 jobs:
-  test:
-    name: Rust ${{matrix.rust}} on ${{matrix.os == 'ubuntu' && 'Linux' || matrix.os == 'macos' && 'macOS' || matrix.os == 'windows' && 'Windows' || 'unknown'}}
+  test-install:
+    name: Install test for Rust ${{matrix.rust}} on ${{matrix.os == 'ubuntu' && 'Linux' || matrix.os == 'macos' && 'macOS' || matrix.os == 'windows' && 'Windows' || 'unknown'}}
     runs-on: ${{matrix.os}}-latest
     strategy:
       fail-fast: false
@@ -37,7 +37,25 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      - name: Run tests
-        uses: ./tests
+      - name: Run test
+        uses: ./tests/install
         with:
           toolchain: ${{matrix.rust}}
+
+  test-default:
+    name: Default test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Run test
+        uses: ./tests/default
+
+  test-override:
+    name: Override test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Run test
+        uses: ./tests/override
diff --git a/tests/default/action.yml b/tests/default/action.yml
new file mode 100644
index 0000000..7ef9941
--- /dev/null
+++ b/tests/default/action.yml
@@ -0,0 +1,43 @@
+name: Default test
+description: Check that the default setting works and that the action may be run multiple times
+
+runs:
+  using: composite
+  steps:
+    - name: Install Rust 1.74.1 (without default)
+      id: toolchain-1-74-1
+      uses: ./
+      with:
+        toolchain: 1.74.1
+
+    - name: Install Rust 1.75.0 (with default)
+      id: toolchain-1-75-0
+      uses: ./
+      with:
+        toolchain: 1.75.0
+        default: true
+
+    - name: 1.74.1 cache key
+      run: echo '${{steps.toolchain-1-74-1.outputs.cachekey}}'
+      shell: bash
+
+    - name: 1.75.0 cache key
+      run: echo '${{steps.toolchain-1-75-0.outputs.cachekey}}'
+      shell: bash
+
+    - name: Default rustc version
+      run: rustc --version
+      shell: bash
+
+    - name: Check 1.74.1 cache key
+      run: cmp -s <(echo ${{steps.toolchain-1-74-1.outputs.cachekey}}) <(echo PLACEHOLDER)
+      shell: bash
+
+    - name: Check 1.75.0 cache key
+      run: cmp -s <(echo ${{steps.toolchain-1-75-0.outputs.cachekey}}) <(echo PLACEHOLDER)
+      shell: bash
+
+    - name: Check default rustc version
+      run: cmp -s <(rustc --version) <(echo PLACEHOLDER)
+      shell: bash
+
diff --git a/tests/action.yml b/tests/install/action.yml
similarity index 73%
rename from tests/action.yml
rename to tests/install/action.yml
index 0def33e..78c97a8 100644
--- a/tests/action.yml
+++ b/tests/install/action.yml
@@ -1,33 +1,34 @@
-name: Test
-description: Run the test suite
+name: Install test
+description: Check that the action works
 
 inputs:
   toolchain:
-    description:
+    description: Rust toolchain name
     required: true
 
 runs:
   using: composite
   steps:
-    - name: Run action for ${{inputs.toolchain}}
+    - name: Install Rust ${{inputs.toolchain}}
       id: toolchain
       uses: ./
       with:
         toolchain: ${{inputs.toolchain}}
 
-    - name: echo ${{'${{steps.toolchain.outputs.cachekey}}'}}
+    - name: Cache key
       run: echo '${{steps.toolchain.outputs.cachekey}}'
       shell: bash
 
-    - name: check ${{'${{steps.toolchain.outputs.cachekey}}'}}
+    - name: Check cache key
       if: inputs.toolchain == '1.62.0'
       run: cmp -s <(echo ${{steps.toolchain.outputs.cachekey}}) <(echo 20220627a831)
       shell: bash
 
-    - run: rustc --version
+    - name: rustc version
+      run: rustc --version
       shell: bash
 
-    - run: cargo init . --bin --name ci
+    - run: cargo init . --bin --name test
       if: inputs.toolchain == 'nightly' || inputs.toolchain == 'beta' || inputs.toolchain == 'stable'
       shell: bash
 
diff --git a/tests/override/action.yml b/tests/override/action.yml
new file mode 100644
index 0000000..20e5416
--- /dev/null
+++ b/tests/override/action.yml
@@ -0,0 +1,32 @@
+name: Override test
+description: Check that the override setting works
+
+runs:
+  using: composite
+  steps:
+    - name: Install Rust stable
+      id: toolchain
+      uses: ./
+      with:
+        toolchain: stable
+        override: true
+
+    - name: Stable cache key
+      run: echo '${{steps.toolchain.outputs.cachekey}}'
+      shell: bash
+
+    - name: Stable rustc version
+      id: rustc
+      run: |
+        echo "version=$(rustc --version)" >> $GITHUB_OUTPUT
+      shell: bash
+
+    - run: cargo init . --bin --name test
+      shell: bash
+
+    - run: echo '1.70.0' > rust-toolchain
+      shell: bash
+
+    - name: Check rustc version is overridden
+      run: cmp -s <(rustc --version) <(echo ${{steps.rustc.outputs.version}})
+      shell: bash