CI: Test MSRV

There are multiple MSRVs in this crate because of the `bitcoin_hashes`
dependency and also the `zeroize` feature.

Add MSRV test jobs for the three MSRVs effected by `bitcoin_hashes`
and also one for the `zeroize` feature.

Author: tcharding

.github/workflows/rust.yml

@@ -50,7 +50,7 @@ jobs:
           DO_NO_STD: true
         run: ./contrib/test.sh
 
-  MSRV:
+  MSRV-1-41:
     name: Test - 1.41.1 toolchain
     runs-on: ubuntu-latest
     strategy:
@@ -66,6 +66,54 @@ jobs:
           DO_FEATURE_MATRIX: true
         run: ./contrib/test.sh
 
+  MSRV-1-48:
+    name: Test - 1.48.1 toolchain
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+    steps:
+      - name: Checkout Crate
+        uses: actions/checkout@v3
+      - name: Checkout Toolchain
+        uses: dtolnay/[email protected]
+      - name: Running test script
+        env:
+          DO_NO_STD: true
+          DO_FEATURE_MATRIX: true
+        run: ./contrib/test.sh
+
+  MSRV-1-51:
+    name: Test - 1.51.1 toolchain
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+    steps:
+      - name: Checkout Crate
+        uses: actions/checkout@v3
+      - name: Checkout Toolchain
+        uses: dtolnay/[email protected]
+      - name: Running test script
+        env:
+          DO_NO_STD: true
+          DO_FEATURE_MATRIX: true
+        run: ./contrib/test.sh
+
+  MSRV-1-56:
+    name: Test - 1.56.0 toolchain
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+    steps:
+      - name: Checkout Crate
+        uses: actions/checkout@v3
+      - name: Checkout Toolchain
+        uses: dtolnay/[email protected]
+      - name: Running test script
+        env:
+          DO_NO_STD: true
+          DO_FEATURE_MATRIX: true
+        run: ./contrib/test.sh
+
   Arch32bit:
     name: Test 32-bit version
     runs-on: ubuntu-latest

README.md

@@ -33,9 +33,9 @@ This crate supports Rust v1.41.1 and up and works with `no_std`.
 
 The `bitcoin_hashes` range dependency effects the MSRV as follows
 
-- `bitcoin_hashes v0.12`: MSRV v1.41.1
-- `bitcoin_hashes v0.13`: MSRV v1.48.0
-- `bitcoin_hashes v0.14`: MSRV v1.56.1
+- `bitcoin_hashes v0.12`: MSRV `v1.41.1`
+- `bitcoin_hashes v0.13`: MSRV `v1.48.0`
+- `bitcoin_hashes v0.14`: MSRV `v1.56.1`
 
 When using older version of Rust, you might have to pin the versions of several crates, for an up-to-date list refer to [`contrib/test.sh`](contrib/test.sh):
 
@@ -47,4 +47,4 @@ cargo update --package "tinyvec" --precise "1.6.0"
 cargo update --package "unicode-normalization" --precise "0.1.22"
 ```
 
-If you enable the `zeroize` feature the MSRV becomes 1.51.
+If you enable the `zeroize` feature the MSRV becomes `v1.51.0`.

contrib/test.sh

@@ -3,23 +3,31 @@
 set -ex
 
 FEATURES="serde rand all-languages chinese-simplified chinese-traditional czech french italian japanese korean portuguese spanish"
+RUSTC_MINOR_VERSION=$(rustc --version | awk '{ split($2,a,"."); print a[2] }')
 
 cargo --version
 rustc --version
 
-# Pin dependencies as required if we are using MSRV toolchain.
-if cargo --version | grep "1\.41"; then
-    cp Cargo-minimal.lock Cargo.lock
-    cargo check --locked
-    rm Cargo.lock
+[ "$RUSTC_MINOR_VERSION" -lt 82 ] && cargo update -p backtrace --precise "0.3.74" --verbose
 
+# Check the minimal lock file for all toolchains we test.
+cp Cargo-minimal.lock Cargo.lock
+cargo check --locked
+rm Cargo.lock
+
+# The crate's lowest MSRV (not lifted by `bitcoin_hashes` dep or `zeroize` feature). 
+if [ "$RUSTC_MINOR_VERSION" -eq 41 ]; then
     cargo update --package "bitcoin_hashes" --precise "0.12.0"
     cargo update --package "rand" --precise "0.6.0"
     cargo update --package "libc" --precise "0.2.151"
     cargo update --package "tinyvec" --precise "1.6.0"
     cargo update --package "unicode-normalization" --precise "0.1.22"
 fi
 
+# `bitcoin_hashes` version raises the crate MSRV, we test with these toolchains explicitly in CI.
+[ "$RUSTC_MINOR_VERSION" -eq 48 ]  && cargo update --package "bitcoin_hashes" --precise "0.13.0"
+[ "$RUSTC_MINOR_VERSION" -eq 56 ]  && cargo update --package "bitcoin_hashes" --precise "0.14.0"
+
 echo "********* Testing std *************"
 # Test without any features other than std first
 cargo test --verbose --no-default-features --features="std"
@@ -34,7 +42,7 @@ do
     cargo build --verbose --features="$feature" --no-default-features
 done
 
-if cargo --version | grep -v "1\.41"; then
+if [ "$RUSTC_MINOR_VERSION" -ge 51 ]; then
     cargo build --verbose --features="zeroize" --no-default-features
 fi